normalize userFollowingsCache / userFollowersCache and add hibernatedUserCache to reduce the number of cache-clears and allow use of caching in many more places

28 files changed, 816 insertions, 581 deletions

diff --git a/packages/backend/src/core/AccountMoveService.ts b/packages/backend/src/core/AccountMoveService.ts
index 738026f753..e107f02796 100644
--- a/packages/backend/src/core/AccountMoveService.ts
+++ b/packages/backend/src/core/AccountMoveService.ts
@@ -26,6 +26,7 @@ import PerUserFollowingChart from '@/core/chart/charts/per-user-following.js';
 import { SystemAccountService } from '@/core/SystemAccountService.js';
 import { RoleService } from '@/core/RoleService.js';
 import { AntennaService } from '@/core/AntennaService.js';
+import { CacheService } from '@/core/CacheService.js';
 
 @Injectable()
 export class AccountMoveService {
@@ -68,6 +69,7 @@ export class AccountMoveService {
 		private systemAccountService: SystemAccountService,
 		private roleService: RoleService,
 		private antennaService: AntennaService,
+		private readonly cacheService: CacheService,
 	) {
 	}
 
@@ -107,12 +109,10 @@ export class AccountMoveService {
 		this.globalEventService.publishMainStream(src.id, 'meUpdated', iObj);
 
 		// Unfollow after 24 hours
-		const followings = await this.followingsRepository.findBy({
-			followerId: src.id,
-		});
-		this.queueService.createDelayedUnfollowJob(followings.map(following => ({
+		const followings = await this.cacheService.userFollowingsCache.fetch(src.id);
+		this.queueService.createDelayedUnfollowJob(Array.from(followings.keys()).map(followeeId => ({
 			from: { id: src.id },
-			to: { id: following.followeeId },
+			to: { id: followeeId },
 		})), process.env.NODE_ENV === 'test' ? 10000 : 1000 * 60 * 60 * 24);
 
 		await this.postMoveProcess(src, dst);
@@ -138,11 +138,9 @@ export class AccountMoveService {
 
 		// follow the new account
 		const proxy = await this.systemAccountService.fetch('proxy');
-		const followings = await this.followingsRepository.findBy({
-			followeeId: src.id,
-			followerHost: IsNull(), // follower is local
-			followerId: Not(proxy.id),
-		});
+		const followings = await this.cacheService.userFollowersCache.fetch(src.id)
+			.then(fs => Array.from(fs.values())
+				.filter(f => f.followerHost == null && f.followerId !== proxy.id));
 		const followJobs = followings.map(following => ({
 			from: { id: following.followerId },
 			to: { id: dst.id },
@@ -318,9 +316,9 @@ export class AccountMoveService {
 		await this.usersRepository.decrement({ id: In(localFollowerIds) }, 'followingCount', 1);
 
 		// Decrease follower counts of local followees by 1.
-		const oldFollowings = await this.followingsRepository.findBy({ followerId: oldAccount.id });
-		if (oldFollowings.length > 0) {
-			await this.usersRepository.decrement({ id: In(oldFollowings.map(following => following.followeeId)) }, 'followersCount', 1);
+		const oldFollowings = await this.cacheService.userFollowingsCache.fetch(oldAccount.id);
+		if (oldFollowings.size > 0) {
+			await this.usersRepository.decrement({ id: In(Array.from(oldFollowings.keys())) }, 'followersCount', 1);
 		}
 
 		// Update instance stats by decreasing remote followers count by the number of local followers who were following the old account.
diff --git a/packages/backend/src/core/CacheService.ts b/packages/backend/src/core/CacheService.ts
index e8b26f8b9b..9c68597441 100644
--- a/packages/backend/src/core/CacheService.ts
+++ b/packages/backend/src/core/CacheService.ts
@@ -6,7 +6,7 @@
 import { Inject, Injectable } from '@nestjs/common';
 import * as Redis from 'ioredis';
 import { In, IsNull } from 'typeorm';
-import type { BlockingsRepository, FollowingsRepository, MutingsRepository, RenoteMutingsRepository, MiUserProfile, UserProfilesRepository, UsersRepository, MiNote } from '@/models/_.js';
+import type { BlockingsRepository, FollowingsRepository, MutingsRepository, RenoteMutingsRepository, MiUserProfile, UserProfilesRepository, UsersRepository, MiNote, MiFollowing } from '@/models/_.js';
 import { MemoryKVCache, RedisKVCache } from '@/misc/cache.js';
 import { QuantumKVCache } from '@/misc/QuantumKVCache.js';
 import type { MiLocalUser, MiUser } from '@/models/User.js';
@@ -46,8 +46,9 @@ export class CacheService implements OnApplicationShutdown {
 	public userBlockingCache: QuantumKVCache<Set<string>>;
 	public userBlockedCache: QuantumKVCache<Set<string>>; // NOTE: 「被」Blockキャッシュ
 	public renoteMutingsCache: QuantumKVCache<Set<string>>;
-	public userFollowingsCache: QuantumKVCache<Map<string, { withReplies: boolean }>>;
-	public userFollowersCache: QuantumKVCache<Set<string>>;
+	public userFollowingsCache: QuantumKVCache<Map<string, Omit<MiFollowing, 'isFollowerHibernated'>>>;
+	public userFollowersCache: QuantumKVCache<Map<string, Omit<MiFollowing, 'isFollowerHibernated'>>>;
+	public hibernatedUserCache: QuantumKVCache<boolean>;
 	protected userFollowStatsCache = new MemoryKVCache<FollowStats>(1000 * 60 * 10); // 10 minutes
 	protected translationsCache: RedisKVCache<CachedTranslationEntity>;
 
@@ -89,36 +90,145 @@ export class CacheService implements OnApplicationShutdown {
 		this.userProfileCache = new QuantumKVCache(this.internalEventService, 'userProfile', {
 			lifetime: 1000 * 60 * 30, // 30m
 			fetcher: (key) => this.userProfilesRepository.findOneByOrFail({ userId: key }),
+			bulkFetcher: userIds => this.userProfilesRepository.findBy({ userId: In(userIds) }).then(ps => ps.map(p => [p.userId, p])),
 		});
 
 		this.userMutingsCache = new QuantumKVCache<Set<string>>(this.internalEventService, 'userMutings', {
 			lifetime: 1000 * 60 * 30, // 30m
 			fetcher: (key) => this.mutingsRepository.find({ where: { muterId: key }, select: ['muteeId'] }).then(xs => new Set(xs.map(x => x.muteeId))),
+			bulkFetcher: muterIds => this.mutingsRepository
+				.createQueryBuilder('muting')
+				.select('"muting"."muterId"', 'muterId')
+				.addSelect('array_agg("muting"."muteeId")', 'muteeIds')
+				.where({ muterId: In(muterIds) })
+				.groupBy('muting.muterId')
+				.getRawMany<{ muterId: string, muteeIds: string[] }>()
+				.then(ms => ms.map(m => [m.muterId, new Set(m.muteeIds)])),
 		});
 
 		this.userBlockingCache = new QuantumKVCache<Set<string>>(this.internalEventService, 'userBlocking', {
 			lifetime: 1000 * 60 * 30, // 30m
 			fetcher: (key) => this.blockingsRepository.find({ where: { blockerId: key }, select: ['blockeeId'] }).then(xs => new Set(xs.map(x => x.blockeeId))),
+			bulkFetcher: blockerIds => this.blockingsRepository
+				.createQueryBuilder('blocking')
+				.select('"blocking"."blockerId"', 'blockerId')
+				.addSelect('array_agg("blocking"."blockeeId")', 'blockeeIds')
+				.where({ blockerId: In(blockerIds) })
+				.groupBy('blocking.blockerId')
+				.getRawMany<{ blockerId: string, blockeeIds: string[] }>()
+				.then(ms => ms.map(m => [m.blockerId, new Set(m.blockeeIds)])),
 		});
 
 		this.userBlockedCache = new QuantumKVCache<Set<string>>(this.internalEventService, 'userBlocked', {
 			lifetime: 1000 * 60 * 30, // 30m
 			fetcher: (key) => this.blockingsRepository.find({ where: { blockeeId: key }, select: ['blockerId'] }).then(xs => new Set(xs.map(x => x.blockerId))),
+			bulkFetcher: blockeeIds => this.blockingsRepository
+				.createQueryBuilder('blocking')
+				.select('"blocking"."blockeeId"', 'blockeeId')
+				.addSelect('array_agg("blocking"."blockeeId")', 'blockeeIds')
+				.where({ blockeeId: In(blockeeIds) })
+				.groupBy('blocking.blockeeId')
+				.getRawMany<{ blockeeId: string, blockerIds: string[] }>()
+				.then(ms => ms.map(m => [m.blockeeId, new Set(m.blockerIds)])),
 		});
 
 		this.renoteMutingsCache = new QuantumKVCache<Set<string>>(this.internalEventService, 'renoteMutings', {
 			lifetime: 1000 * 60 * 30, // 30m
 			fetcher: (key) => this.renoteMutingsRepository.find({ where: { muterId: key }, select: ['muteeId'] }).then(xs => new Set(xs.map(x => x.muteeId))),
+			bulkFetcher: muterIds => this.renoteMutingsRepository
+				.createQueryBuilder('muting')
+				.select('"muting"."muterId"', 'muterId')
+				.addSelect('array_agg("muting"."muteeId")', 'muteeIds')
+				.where({ muterId: In(muterIds) })
+				.groupBy('muting.muterId')
+				.getRawMany<{ muterId: string, muteeIds: string[] }>()
+				.then(ms => ms.map(m => [m.muterId, new Set(m.muteeIds)])),
 		});
 
-		this.userFollowingsCache = new QuantumKVCache<Map<string, { withReplies: boolean }>>(this.internalEventService, 'userFollowings', {
+		this.userFollowingsCache = new QuantumKVCache<Map<string, Omit<MiFollowing, 'isFollowerHibernated'>>>(this.internalEventService, 'userFollowings', {
 			lifetime: 1000 * 60 * 30, // 30m
-			fetcher: (key) => this.followingsRepository.find({ where: { followerId: key }, select: ['followeeId', 'withReplies'] }).then(xs => new Map(xs.map(f => [f.followeeId, { withReplies: f.withReplies }]))),
+			fetcher: (key) => this.followingsRepository.findBy({ followerId: key }).then(xs => new Map(xs.map(f => [f.followeeId, f]))),
+			bulkFetcher: followerIds => this.followingsRepository
+				.findBy({ followerId: In(followerIds) })
+				.then(fs => fs
+					.reduce((groups, f) => {
+						let group = groups.get(f.followerId);
+						if (!group) {
+							group = new Map();
+							groups.set(f.followerId, group);
+						}
+						group.set(f.followeeId, f);
+						return groups;
+					}, {} as Map<string, Map<string, Omit<MiFollowing, 'isFollowerHibernated'>>>)),
 		});
 
-		this.userFollowersCache = new QuantumKVCache<Set<string>>(this.internalEventService, 'userFollowers', {
+		this.userFollowersCache = new QuantumKVCache<Map<string, Omit<MiFollowing, 'isFollowerHibernated'>>>(this.internalEventService, 'userFollowers', {
 			lifetime: 1000 * 60 * 30, // 30m
-			fetcher: (key) => this.followingsRepository.find({ where: { followeeId: key }, select: ['followerId'] }).then(xs => new Set(xs.map(x => x.followerId))),
+			fetcher: followeeId => this.followingsRepository.findBy({ followeeId: followeeId }).then(xs => new Map(xs.map(x => [x.followerId, x]))),
+			bulkFetcher: followeeIds => this.followingsRepository
+				.findBy({ followeeId: In(followeeIds) })
+				.then(fs => fs
+					.reduce((groups, f) => {
+						let group = groups.get(f.followeeId);
+						if (!group) {
+							group = new Map();
+							groups.set(f.followeeId, group);
+						}
+						group.set(f.followerId, f);
+						return groups;
+					}, {} as Map<string, Map<string, Omit<MiFollowing, 'isFollowerHibernated'>>>)),
+		});
+
+		this.hibernatedUserCache = new QuantumKVCache<boolean>(this.internalEventService, 'hibernatedUsers', {
+			lifetime: 1000 * 60 * 30, // 30m
+			fetcher: async userId => {
+				const { isHibernated } = await this.usersRepository.findOneOrFail({
+					where: { id: userId },
+					select: { isHibernated: true },
+				});
+				return isHibernated;
+			},
+			bulkFetcher: async userIds => {
+				const results = await this.usersRepository.find({
+					where: { id: In(userIds) },
+					select: { id: true, isHibernated: true },
+				});
+				return results.map(({ id, isHibernated }) => [id, isHibernated]);
+			},
+			onChanged: async userIds => {
+				// We only update local copies since each process will get this event, but we can have user objects in multiple different caches.
+				// Before doing anything else we must "find" all the objects to update.
+				const userObjects = new Map<string, MiUser[]>();
+				const toUpdate: string[] = [];
+				for (const uid of userIds) {
+					const toAdd: MiUser[] = [];
+
+					const localUserById = this.localUserByIdCache.get(uid);
+					if (localUserById) toAdd.push(localUserById);
+
+					const userById = this.userByIdCache.get(uid);
+					if (userById) toAdd.push(userById);
+
+					if (toAdd.length > 0) {
+						toUpdate.push(uid);
+						userObjects.set(uid, toAdd);
+					}
+				}
+
+				// In many cases, we won't have to do anything.
+				// Skipping the DB fetch ensures that this remains a single-step synchronous process.
+				if (toUpdate.length > 0) {
+					const hibernations = await this.usersRepository.find({ where: { id: In(toUpdate) }, select: { id: true, isHibernated: true } });
+					for (const { id, isHibernated } of hibernations) {
+						const users = userObjects.get(id);
+						if (users) {
+							for (const u of users) {
+								u.isHibernated = isHibernated;
+							}
+						}
+					}
+				}
+			},
 		});
 
 		this.translationsCache = new RedisKVCache<CachedTranslationEntity>(this.redisClient, 'translations', {
@@ -161,6 +271,7 @@ export class CacheService implements OnApplicationShutdown {
 								this.renoteMutingsCache.delete(body.id),
 								this.userFollowingsCache.delete(body.id),
 								this.userFollowersCache.delete(body.id),
+								this.hibernatedUserCache.delete(body.id),
 							]);
 						}
 					} else {
@@ -312,142 +423,6 @@ export class CacheService implements OnApplicationShutdown {
 	}
 
 	@bindThis
-	public async getUserFollowings(userIds: Iterable<string>): Promise<Map<string, Map<string, { withReplies: boolean }>>> {
-		const followings = new Map<string, Map<string, { withReplies: boolean }>>();
-
-		const toFetch: string[] = [];
-		for (const userId of userIds) {
-			const fromCache = this.userFollowingsCache.get(userId);
-			if (fromCache) {
-				followings.set(userId, fromCache);
-			} else {
-				toFetch.push(userId);
-			}
-		}
-
-		if (toFetch.length > 0) {
-			const fetchedFollowings = await this.followingsRepository
-				.createQueryBuilder('following')
-				.select([
-					'following.followerId',
-					'following.followeeId',
-					'following.withReplies',
-				])
-				.where({
-					followerId: In(toFetch),
-				})
-				.getMany();
-
-			const toCache = new Map<string, Map<string, { withReplies: boolean }>>();
-
-			// Pivot to a map
-			for (const { followerId, followeeId, withReplies } of fetchedFollowings) {
-				// Queue for cache
-				let cacheMap = toCache.get(followerId);
-				if (!cacheMap) {
-					cacheMap = new Map();
-					toCache.set(followerId, cacheMap);
-				}
-				cacheMap.set(followeeId, { withReplies });
-
-				// Queue for return
-				let returnSet = followings.get(followerId);
-				if (!returnSet) {
-					returnSet = new Map();
-					followings.set(followerId, returnSet);
-				}
-				returnSet.set(followeeId, { withReplies });
-			}
-
-			// Update cache to speed up future calls
-			this.userFollowingsCache.addMany(toCache);
-		}
-
-		return followings;
-	}
-
-	@bindThis
-	public async getUserBlockers(userIds: Iterable<string>): Promise<Map<string, Set<string>>> {
-		const blockers = new Map<string, Set<string>>();
-
-		const toFetch: string[] = [];
-		for (const userId of userIds) {
-			const fromCache = this.userBlockedCache.get(userId);
-			if (fromCache) {
-				blockers.set(userId, fromCache);
-			} else {
-				toFetch.push(userId);
-			}
-		}
-
-		if (toFetch.length > 0) {
-			const fetchedBlockers = await this.blockingsRepository.createQueryBuilder('blocking')
-				.select([
-					'blocking.blockerId',
-					'blocking.blockeeId',
-				])
-				.where({
-					blockeeId: In(toFetch),
-				})
-				.getMany();
-
-			const toCache = new Map<string, Set<string>>();
-
-			// Pivot to a map
-			for (const { blockerId, blockeeId } of fetchedBlockers) {
-				// Queue for cache
-				let cacheSet = toCache.get(blockeeId);
-				if (!cacheSet) {
-					cacheSet = new Set();
-					toCache.set(blockeeId, cacheSet);
-				}
-				cacheSet.add(blockerId);
-
-				// Queue for return
-				let returnSet = blockers.get(blockeeId);
-				if (!returnSet) {
-					returnSet = new Set();
-					blockers.set(blockeeId, returnSet);
-				}
-				returnSet.add(blockerId);
-			}
-
-			// Update cache to speed up future calls
-			this.userBlockedCache.addMany(toCache);
-		}
-
-		return blockers;
-	}
-
-	public async getUserProfiles(userIds: Iterable<string>): Promise<Map<string, MiUserProfile>> {
-		const profiles = new Map<string, MiUserProfile>;
-
-		const toFetch: string[] = [];
-		for (const userId of userIds) {
-			const fromCache = this.userProfileCache.get(userId);
-			if (fromCache) {
-				profiles.set(userId, fromCache);
-			} else {
-				toFetch.push(userId);
-			}
-		}
-
-		if (toFetch.length > 0) {
-			const fetched = await this.userProfilesRepository.findBy({
-				userId: In(toFetch),
-			});
-
-			for (const profile of fetched) {
-				profiles.set(profile.userId, profile);
-			}
-
-			const toCache = new Map(fetched.map(p => [p.userId, p]));
-			this.userProfileCache.addMany(toCache);
-		}
-
-		return profiles;
-	}
-
 	public async getUsers(userIds: Iterable<string>): Promise<Map<string, MiUser>> {
 		const users = new Map<string, MiUser>;
 
@@ -476,6 +451,61 @@ export class CacheService implements OnApplicationShutdown {
 	}
 
 	@bindThis
+	public async isFollowing(follower: string | { id: string }, followee: string | { id: string }): Promise<boolean> {
+		const followerId = typeof(follower) === 'string' ? follower : follower.id;
+		const followeeId = typeof(followee) === 'string' ? followee : followee.id;
+
+		// This lets us use whichever one is in memory, falling back to DB fetch via userFollowingsCache.
+		return this.userFollowersCache.get(followeeId)?.has(followerId)
+		?? (await this.userFollowingsCache.fetch(followerId)).has(followeeId);
+	}
+
+	/**
+	 * Returns all hibernated followers.
+	 */
+	@bindThis
+	public async getHibernatedFollowers(followeeId: string): Promise<MiFollowing[]> {
+		const followers = await this.getFollowersWithHibernation(followeeId);
+		return followers.filter(f => f.isFollowerHibernated);
+	}
+
+	/**
+	 * Returns all non-hibernated followers.
+	 */
+	@bindThis
+	public async getNonHibernatedFollowers(followeeId: string): Promise<MiFollowing[]> {
+		const followers = await this.getFollowersWithHibernation(followeeId);
+		return followers.filter(f => !f.isFollowerHibernated);
+	}
+
+	/**
+	 * Returns follower relations with populated isFollowerHibernated.
+	 * If you don't need this field, then please use userFollowersCache directly for reduced overhead.
+	 */
+	@bindThis
+	public async getFollowersWithHibernation(followeeId: string): Promise<MiFollowing[]> {
+		const followers = await this.userFollowersCache.fetch(followeeId);
+		const hibernations = await this.hibernatedUserCache.fetchMany(followers.keys()).then(fs => fs.reduce((map, f) => {
+			map.set(f[0], f[1]);
+			return map;
+		}, new Map<string, boolean>));
+		return Array.from(followers.values()).map(following => ({
+			...following,
+			isFollowerHibernated: hibernations.get(following.followerId) ?? false,
+		}));
+	}
+
+	/**
+	 * Refreshes follower and following relations for the given user.
+	 */
+	@bindThis
+	public async refreshFollowRelationsFor(userId: string): Promise<void> {
+		const followings = await this.userFollowingsCache.refresh(userId);
+		const followees = Array.from(followings.values()).map(f => f.followeeId);
+		await this.userFollowersCache.deleteMany(followees);
+	}
+
+	@bindThis
 	public clear(): void {
 		this.userByIdCache.clear();
 		this.localUserByNativeTokenCache.clear();
diff --git a/packages/backend/src/core/GlobalEventService.ts b/packages/backend/src/core/GlobalEventService.ts
index de35e9db19..c146811331 100644
--- a/packages/backend/src/core/GlobalEventService.ts
+++ b/packages/backend/src/core/GlobalEventService.ts
@@ -265,7 +265,7 @@ export interface InternalEventTypes {
 	unmute: { muterId: MiUser['id']; muteeId: MiUser['id']; };
 	userListMemberAdded: { userListId: MiUserList['id']; memberId: MiUser['id']; };
 	userListMemberRemoved: { userListId: MiUserList['id']; memberId: MiUser['id']; };
-	quantumCacheUpdated: { name: string, keys: string[], op: 's' | 'd' };
+	quantumCacheUpdated: { name: string, keys: string[] };
 }
 
 type EventTypesToEventPayload<T> = EventUnionFromDictionary<UndefinedAsNullAll<SerializedAll<T>>>;
diff --git a/packages/backend/src/core/NoteCreateService.ts b/packages/backend/src/core/NoteCreateService.ts
index 4dceb6e953..a9f4083446 100644
--- a/packages/backend/src/core/NoteCreateService.ts
+++ b/packages/backend/src/core/NoteCreateService.ts
@@ -606,11 +606,11 @@ export class NoteCreateService implements OnApplicationShutdown {
 		}
 
 		if (data.reply == null) {
-			// TODO: キャッシュ
-			this.followingsRepository.findBy({
-				followeeId: user.id,
-				notify: 'normal',
-			}).then(async followings => {
+			this.cacheService.userFollowersCache.fetch(user.id).then(async followingsMap => {
+				const followings = Array
+					.from(followingsMap.values())
+					.filter(f => f.notify === 'normal');
+
 				if (note.visibility !== 'specified') {
 					const isPureRenote = this.isRenote(data) && !this.isQuote(data) ? true : false;
 					for (const following of followings) {
@@ -948,14 +948,7 @@ export class NoteCreateService implements OnApplicationShutdown {
 			// TODO: キャッシュ？
 			// eslint-disable-next-line prefer-const
 			let [followings, userListMemberships] = await Promise.all([
-				this.followingsRepository.find({
-					where: {
-						followeeId: user.id,
-						followerHost: IsNull(),
-						isFollowerHibernated: false,
-					},
-					select: ['followerId', 'withReplies'],
-				}),
+				this.cacheService.getNonHibernatedFollowers(user.id),
 				this.userListMembershipsRepository.find({
 					where: {
 						userId: user.id,
@@ -1072,17 +1065,19 @@ export class NoteCreateService implements OnApplicationShutdown {
 		});
 
 		if (hibernatedUsers.length > 0) {
-			this.usersRepository.update({
-				id: In(hibernatedUsers.map(x => x.id)),
-			}, {
-				isHibernated: true,
-			});
-
-			this.followingsRepository.update({
-				followerId: In(hibernatedUsers.map(x => x.id)),
-			}, {
-				isFollowerHibernated: true,
-			});
+			await Promise.all([
+				this.usersRepository.update({
+					id: In(hibernatedUsers.map(x => x.id)),
+				}, {
+					isHibernated: true,
+				}),
+				this.followingsRepository.update({
+					followerId: In(hibernatedUsers.map(x => x.id)),
+				}, {
+					isFollowerHibernated: true,
+				}),
+				this.cacheService.hibernatedUserCache.setMany(hibernatedUsers.map(x => [x.id, true])),
+			]);
 		}
 	}
 
diff --git a/packages/backend/src/core/NoteEditService.ts b/packages/backend/src/core/NoteEditService.ts
index 34af1c76dd..a359381573 100644
--- a/packages/backend/src/core/NoteEditService.ts
+++ b/packages/backend/src/core/NoteEditService.ts
@@ -833,14 +833,7 @@ export class NoteEditService implements OnApplicationShutdown {
 			// TODO: キャッシュ？
 			// eslint-disable-next-line prefer-const
 			let [followings, userListMemberships] = await Promise.all([
-				this.followingsRepository.find({
-					where: {
-						followeeId: user.id,
-						followerHost: IsNull(),
-						isFollowerHibernated: false,
-					},
-					select: ['followerId', 'withReplies'],
-				}),
+				this.cacheService.getNonHibernatedFollowers(user.id),
 				this.userListMembershipsRepository.find({
 					where: {
 						userId: user.id,
@@ -957,17 +950,19 @@ export class NoteEditService implements OnApplicationShutdown {
 		});
 
 		if (hibernatedUsers.length > 0) {
-			this.usersRepository.update({
-				id: In(hibernatedUsers.map(x => x.id)),
-			}, {
-				isHibernated: true,
-			});
-
-			this.followingsRepository.update({
-				followerId: In(hibernatedUsers.map(x => x.id)),
-			}, {
-				isFollowerHibernated: true,
-			});
+			await Promise.all([
+				this.usersRepository.update({
+					id: In(hibernatedUsers.map(x => x.id)),
+				}, {
+					isHibernated: true,
+				}),
+				this.followingsRepository.update({
+					followerId: In(hibernatedUsers.map(x => x.id)),
+				}, {
+					isFollowerHibernated: true,
+				}),
+				this.cacheService.hibernatedUserCache.setMany(hibernatedUsers.map(x => [x.id, true])),
+			]);
 		}
 	}
 
diff --git a/packages/backend/src/core/UserFollowingService.ts b/packages/backend/src/core/UserFollowingService.ts
index 6a6c9a3000..8470872eac 100644
--- a/packages/backend/src/core/UserFollowingService.ts
+++ b/packages/backend/src/core/UserFollowingService.ts
@@ -147,12 +147,7 @@ export class UserFollowingService implements OnModuleInit {
 			if (blocked) throw new IdentifiableError('3338392a-f764-498d-8855-db939dcf8c48', 'blocked');
 		}
 
-		if (await this.followingsRepository.exists({
-			where: {
-				followerId: follower.id,
-				followeeId: followee.id,
-			},
-		})) {
+		if (await this.cacheService.isFollowing(follower, followee)) {
 			// すでにフォロー関係が存在している場合
 			if (this.userEntityService.isRemoteUser(follower) && this.userEntityService.isLocalUser(followee)) {
 				// リモート → ローカル: acceptを送り返しておしまい
@@ -180,24 +175,14 @@ export class UserFollowingService implements OnModuleInit {
 			let autoAccept = false;
 
 			// 鍵アカウントであっても、既にフォローされていた場合はスルー
-			const isFollowing = await this.followingsRepository.exists({
-				where: {
-					followerId: follower.id,
-					followeeId: followee.id,
-				},
-			});
+			const isFollowing = await this.cacheService.isFollowing(follower, followee);
 			if (isFollowing) {
 				autoAccept = true;
 			}
 
 			// フォローしているユーザーは自動承認オプション
 			if (!autoAccept && (this.userEntityService.isLocalUser(followee) && followeeProfile.autoAcceptFollowed)) {
-				const isFollowed = await this.followingsRepository.exists({
-					where: {
-						followerId: followee.id,
-						followeeId: follower.id,
-					},
-				});
+				const isFollowed = await this.cacheService.isFollowing(followee, follower); // intentionally reversed parameters
 
 				if (isFollowed) autoAccept = true;
 			}
@@ -206,12 +191,7 @@ export class UserFollowingService implements OnModuleInit {
 			if (followee.isLocked && !autoAccept) {
 				autoAccept = !!(await this.accountMoveService.validateAlsoKnownAs(
 					follower,
-					(oldSrc, newSrc) => this.followingsRepository.exists({
-						where: {
-							followeeId: followee.id,
-							followerId: newSrc.id,
-						},
-					}),
+					(oldSrc, newSrc) => this.cacheService.isFollowing(newSrc, followee),
 					true,
 				));
 			}
@@ -366,32 +346,29 @@ export class UserFollowingService implements OnModuleInit {
 		},
 		silent = false,
 	): Promise<void> {
-		const following = await this.followingsRepository.findOne({
-			relations: {
-				follower: true,
-				followee: true,
-			},
-			where: {
-				followerId: follower.id,
-				followeeId: followee.id,
-			},
-		});
+		const [
+			followerUser,
+			followeeUser,
+			following,
+		] = await Promise.all([
+			this.cacheService.findUserById(follower.id),
+			this.cacheService.findUserById(followee.id),
+			this.cacheService.userFollowingsCache.fetch(follower.id).then(fs => fs.get(followee.id)),
+		]);
 
-		if (following === null || !following.follower || !following.followee) {
+		if (following == null) {
 			this.logger.warn('フォロー解除がリクエストされましたがフォローしていませんでした');
 			return;
 		}
 
 		await this.followingsRepository.delete(following.id);
+		await this.internalEventService.emit('unfollow', { followerId: follower.id, followeeId: followee.id });
 
-		// Handled by CacheService
-		// this.cacheService.userFollowingsCache.refresh(follower.id);
-
-		this.decrementFollowing(following.follower, following.followee);
+		this.decrementFollowing(followerUser, followeeUser);
 
 		if (!silent && this.userEntityService.isLocalUser(follower)) {
 			// Publish unfollow event
-			this.userEntityService.pack(followee.id, follower, {
+			this.userEntityService.pack(followeeUser, follower, {
 				schema: 'UserDetailedNotMe',
 			}).then(async packed => {
 				this.globalEventService.publishMainStream(follower.id, 'unfollow', packed);
@@ -416,8 +393,6 @@ export class UserFollowingService implements OnModuleInit {
 		follower: MiUser,
 		followee: MiUser,
 	): Promise<void> {
-		await this.internalEventService.emit('unfollow', { followerId: follower.id, followeeId: followee.id });
-
 		// Neither followee nor follower has moved.
 		if (!follower.movedToUri && !followee.movedToUri) {
 			//#region Decrement following / followers counts
@@ -691,22 +666,22 @@ export class UserFollowingService implements OnModuleInit {
 	 */
 	@bindThis
 	private async removeFollow(followee: Both, follower: Both): Promise<void> {
-		const following = await this.followingsRepository.findOne({
-			relations: {
-				followee: true,
-				follower: true,
-			},
-			where: {
-				followeeId: followee.id,
-				followerId: follower.id,
-			},
-		});
+		const [
+			followerUser,
+			followeeUser,
+			following,
+		] = await Promise.all([
+			this.cacheService.findUserById(follower.id),
+			this.cacheService.findUserById(followee.id),
+			this.cacheService.userFollowingsCache.fetch(follower.id).then(fs => fs.get(followee.id)),
+		]);
 
-		if (!following || !following.followee || !following.follower) return;
+		if (!following) return;
 
 		await this.followingsRepository.delete(following.id);
+		await this.internalEventService.emit('unfollow', { followerId: follower.id, followeeId: followee.id });
 
-		this.decrementFollowing(following.follower, following.followee);
+		this.decrementFollowing(followerUser, followeeUser);
 	}
 
 	/**
@@ -737,36 +712,26 @@ export class UserFollowingService implements OnModuleInit {
 	}
 
 	@bindThis
-	public getFollowees(userId: MiUser['id']) {
-		return this.followingsRepository.createQueryBuilder('following')
-			.select('following.followeeId')
-			.where('following.followerId = :followerId', { followerId: userId })
-			.getMany();
+	public async getFollowees(userId: MiUser['id']) {
+		const followings = await this.cacheService.userFollowingsCache.fetch(userId);
+		return Array.from(followings.values());
 	}
 
 	@bindThis
-	public isFollowing(followerId: MiUser['id'], followeeId: MiUser['id']) {
-		return this.followingsRepository.exists({
-			where: {
-				followerId,
-				followeeId,
-			},
-		});
+	public async isFollowing(followerId: MiUser['id'], followeeId: MiUser['id']) {
+		return this.cacheService.isFollowing(followerId, followeeId);
 	}
 
 	@bindThis
 	public async isMutual(aUserId: MiUser['id'], bUserId: MiUser['id']) {
-		const count = await this.followingsRepository.createQueryBuilder('following')
-			.where(new Brackets(qb => {
-				qb.where('following.followerId = :aUserId', { aUserId })
-					.andWhere('following.followeeId = :bUserId', { bUserId });
-			}))
-			.orWhere(new Brackets(qb => {
-				qb.where('following.followerId = :bUserId', { bUserId })
-					.andWhere('following.followeeId = :aUserId', { aUserId });
-			}))
-			.getCount();
+		const [
+			isFollowing,
+			isFollowed,
+		] = await Promise.all([
+			this.isFollowing(aUserId, bUserId),
+			this.isFollowing(bUserId, aUserId),
+		]);
 
-		return count === 2;
+		return isFollowing && isFollowed;
 	}
 }
diff --git a/packages/backend/src/core/UserService.ts b/packages/backend/src/core/UserService.ts
index 1f471513f3..4a04910105 100644
--- a/packages/backend/src/core/UserService.ts
+++ b/packages/backend/src/core/UserService.ts
@@ -10,6 +10,7 @@ import { DI } from '@/di-symbols.js';
 import { bindThis } from '@/decorators.js';
 import { SystemWebhookService } from '@/core/SystemWebhookService.js';
 import { UserEntityService } from '@/core/entities/UserEntityService.js';
+import { CacheService } from '@/core/CacheService.js';
 
 @Injectable()
 export class UserService {
@@ -20,6 +21,7 @@ export class UserService {
 		private followingsRepository: FollowingsRepository,
 		private systemWebhookService: SystemWebhookService,
 		private userEntityService: UserEntityService,
+		private readonly cacheService: CacheService,
 	) {
 	}
 
@@ -38,14 +40,17 @@ export class UserService {
 				});
 			const wokeUp = result.isHibernated;
 			if (wokeUp) {
-				this.usersRepository.update(user.id, {
-					isHibernated: false,
-				});
-				this.followingsRepository.update({
-					followerId: user.id,
-				}, {
-					isFollowerHibernated: false,
-				});
+				await Promise.all([
+					this.usersRepository.update(user.id, {
+						isHibernated: false,
+					}),
+					this.followingsRepository.update({
+						followerId: user.id,
+					}, {
+						isFollowerHibernated: false,
+					}),
+					this.cacheService.hibernatedUserCache.set(user.id, false),
+				]);
 			}
 		} else {
 			this.usersRepository.update(user.id, {
diff --git a/packages/backend/src/core/UserSuspendService.ts b/packages/backend/src/core/UserSuspendService.ts
index 30dcaa6f7d..f375dff862 100644
--- a/packages/backend/src/core/UserSuspendService.ts
+++ b/packages/backend/src/core/UserSuspendService.ts
@@ -16,6 +16,7 @@ import { bindThis } from '@/decorators.js';
 import { RelationshipJobData } from '@/queue/types.js';
 import { ModerationLogService } from '@/core/ModerationLogService.js';
 import { isSystemAccount } from '@/misc/is-system-account.js';
+import { CacheService } from '@/core/CacheService.js';
 
 @Injectable()
 export class UserSuspendService {
@@ -34,6 +35,7 @@ export class UserSuspendService {
 		private globalEventService: GlobalEventService,
 		private apRendererService: ApRendererService,
 		private moderationLogService: ModerationLogService,
+		private readonly cacheService: CacheService,
 	) {
 	}
 
@@ -143,12 +145,8 @@ export class UserSuspendService {
 
 	@bindThis
 	private async unFollowAll(follower: MiUser) {
-		const followings = await this.followingsRepository.find({
-			where: {
-				followerId: follower.id,
-				followeeId: Not(IsNull()),
-			},
-		});
+		const followings = await this.cacheService.userFollowingsCache.fetch(follower.id)
+			.then(fs => Array.from(fs.values()).filter(f => f.followeeHost != null));
 
 		const jobs: RelationshipJobData[] = [];
 		for (const following of followings) {
diff --git a/packages/backend/src/core/activitypub/ApDeliverManagerService.ts b/packages/backend/src/core/activitypub/ApDeliverManagerService.ts
index 746af41f55..86747f2508 100644
--- a/packages/backend/src/core/activitypub/ApDeliverManagerService.ts
+++ b/packages/backend/src/core/activitypub/ApDeliverManagerService.ts
@@ -5,7 +5,6 @@
 
 import { Inject, Injectable } from '@nestjs/common';
 import { IsNull, Not } from 'typeorm';
-import { UnrecoverableError } from 'bullmq';
 import { DI } from '@/di-symbols.js';
 import type { FollowingsRepository } from '@/models/_.js';
 import type { MiLocalUser, MiRemoteUser, MiUser } from '@/models/User.js';
@@ -14,6 +13,7 @@ import { UserEntityService } from '@/core/entities/UserEntityService.js';
 import { bindThis } from '@/decorators.js';
 import type { IActivity } from '@/core/activitypub/type.js';
 import { ThinUser } from '@/queue/types.js';
+import { CacheService } from '@/core/CacheService.js';
 
 interface IRecipe {
 	type: string;
@@ -41,16 +41,14 @@ class DeliverManager {
 
 	/**
 	 * Constructor
-	 * @param userEntityService
-	 * @param followingsRepository
 	 * @param queueService
+	 * @param cacheService
 	 * @param actor Actor
 	 * @param activity Activity to deliver
 	 */
 	constructor(
-		private userEntityService: UserEntityService,
-		private followingsRepository: FollowingsRepository,
 		private queueService: QueueService,
+		private readonly cacheService: CacheService,
 
 		actor: { id: MiUser['id']; host: null; },
 		activity: IActivity | null,
@@ -114,24 +112,23 @@ class DeliverManager {
 		// Process follower recipes first to avoid duplication when processing direct recipes later.
 		if (this.recipes.some(r => isFollowers(r))) {
 			// followers deliver
-			// TODO: SELECT DISTINCT ON ("followerSharedInbox") "followerSharedInbox" みたいな問い合わせにすればよりパフォーマンス向上できそう
 			// ただ、sharedInboxがnullなリモートユーザーも稀におり、その対応ができなさそう？
-			const followers = await this.followingsRepository.find({
-				where: {
-					followeeId: this.actor.id,
-					followerHost: Not(IsNull()),
-				},
-				select: {
-					followerSharedInbox: true,
-					followerInbox: true,
-					followerId: true,
-				},
-			});
+			const followers = await this.cacheService.userFollowingsCache
+				.fetch(this.actor.id)
+				.then(f => Array
+					.from(f.values())
+					.filter(f => f.followerHost != null)
+					.map(f => ({
+						followerInbox: f.followerInbox,
+						followerSharedInbox: f.followerSharedInbox,
+					})));
 
 			for (const following of followers) {
-				const inbox = following.followerSharedInbox ?? following.followerInbox;
-				if (inbox === null) throw new UnrecoverableError(`deliver failed for ${this.actor.id}: follower ${following.followerId} inbox is null`);
-				inboxes.set(inbox, following.followerSharedInbox != null);
+				if (following.followerSharedInbox) {
+					inboxes.set(following.followerSharedInbox, true);
+				} else if (following.followerInbox) {
+					inboxes.set(following.followerInbox, false);
+				}
 			}
 		}
 
@@ -153,11 +150,8 @@ class DeliverManager {
 @Injectable()
 export class ApDeliverManagerService {
 	constructor(
-		@Inject(DI.followingsRepository)
-		private followingsRepository: FollowingsRepository,
-
-		private userEntityService: UserEntityService,
 		private queueService: QueueService,
+		private readonly cacheService: CacheService,
 	) {
 	}
 
@@ -169,9 +163,8 @@ export class ApDeliverManagerService {
 	@bindThis
 	public async deliverToFollowers(actor: { id: MiLocalUser['id']; host: null; }, activity: IActivity): Promise<void> {
 		const manager = new DeliverManager(
-			this.userEntityService,
-			this.followingsRepository,
 			this.queueService,
+			this.cacheService,
 			actor,
 			activity,
 		);
@@ -188,9 +181,8 @@ export class ApDeliverManagerService {
 	@bindThis
 	public async deliverToUser(actor: { id: MiLocalUser['id']; host: null; }, activity: IActivity, to: MiRemoteUser): Promise<void> {
 		const manager = new DeliverManager(
-			this.userEntityService,
-			this.followingsRepository,
 			this.queueService,
+			this.cacheService,
 			actor,
 			activity,
 		);
@@ -207,9 +199,8 @@ export class ApDeliverManagerService {
 	@bindThis
 	public async deliverToUsers(actor: { id: MiLocalUser['id']; host: null; }, activity: IActivity, targets: MiRemoteUser[]): Promise<void> {
 		const manager = new DeliverManager(
-			this.userEntityService,
-			this.followingsRepository,
 			this.queueService,
+			this.cacheService,
 			actor,
 			activity,
 		);
@@ -220,9 +211,8 @@ export class ApDeliverManagerService {
 	@bindThis
 	public createDeliverManager(actor: { id: MiUser['id']; host: null; }, activity: IActivity | null): DeliverManager {
 		return new DeliverManager(
-			this.userEntityService,
-			this.followingsRepository,
 			this.queueService,
+			this.cacheService,
 
 			actor,
 			activity,
diff --git a/packages/backend/src/core/activitypub/ApInboxService.ts b/packages/backend/src/core/activitypub/ApInboxService.ts
index 7c26deb00f..009d4cbd39 100644
--- a/packages/backend/src/core/activitypub/ApInboxService.ts
+++ b/packages/backend/src/core/activitypub/ApInboxService.ts
@@ -37,6 +37,7 @@ import InstanceChart from '@/core/chart/charts/instance.js';
 import FederationChart from '@/core/chart/charts/federation.js';
 import { FetchInstanceMetadataService } from '@/core/FetchInstanceMetadataService.js';
 import { UpdateInstanceQueue } from '@/core/UpdateInstanceQueue.js';
+import { CacheService } from '@/core/CacheService.js';
 import { getApHrefNullable, getApId, getApIds, getApType, getNullableApId, isAccept, isActor, isAdd, isAnnounce, isApObject, isBlock, isCollectionOrOrderedCollection, isCreate, isDelete, isFlag, isFollow, isLike, isDislike, isMove, isPost, isReject, isRemove, isTombstone, isUndo, isUpdate, validActor, validPost, isActivity, IObjectWithId } from './type.js';
 import { ApNoteService } from './models/ApNoteService.js';
 import { ApLoggerService } from './ApLoggerService.js';
@@ -98,6 +99,7 @@ export class ApInboxService {
 		private readonly instanceChart: InstanceChart,
 		private readonly federationChart: FederationChart,
 		private readonly updateInstanceQueue: UpdateInstanceQueue,
+		private readonly cacheService: CacheService,
 	) {
 		this.logger = this.apLoggerService.logger;
 	}
@@ -766,12 +768,7 @@ export class ApInboxService {
 			return 'skip: follower not found';
 		}
 
-		const isFollowing = await this.followingsRepository.exists({
-			where: {
-				followerId: follower.id,
-				followeeId: actor.id,
-			},
-		});
+		const isFollowing = await this.cacheService.userFollowingsCache.fetch(follower.id).then(f => f.has(actor.id));
 
 		if (isFollowing) {
 			await this.userFollowingService.unfollow(follower, actor);
@@ -830,12 +827,7 @@ export class ApInboxService {
 			},
 		});
 
-		const isFollowing = await this.followingsRepository.exists({
-			where: {
-				followerId: actor.id,
-				followeeId: followee.id,
-			},
-		});
+		const isFollowing = await this.cacheService.userFollowingsCache.fetch(actor.id).then(f => f.has(followee.id));
 
 		if (requestExist) {
 			await this.userFollowingService.cancelFollowRequest(followee, actor);
diff --git a/packages/backend/src/core/activitypub/models/ApPersonService.ts b/packages/backend/src/core/activitypub/models/ApPersonService.ts
index b7aa036068..29f7459219 100644
--- a/packages/backend/src/core/activitypub/models/ApPersonService.ts
+++ b/packages/backend/src/core/activitypub/models/ApPersonService.ts
@@ -741,10 +741,17 @@ export class ApPersonService implements OnModuleInit, OnApplicationShutdown {
 		this.hashtagService.updateUsertags(exist, tags);
 
 		// 該当ユーザーが既にフォロワーになっていた場合はFollowingもアップデートする
-		await this.followingsRepository.update(
-			{ followerId: exist.id },
-			{ followerSharedInbox: person.sharedInbox ?? person.endpoints?.sharedInbox ?? null },
-		);
+		if (exist.inbox !== person.inbox || exist.sharedInbox !== (person.sharedInbox ?? person.endpoints?.sharedInbox)) {
+			await this.followingsRepository.update(
+				{ followerId: exist.id },
+				{
+					followerInbox: person.inbox,
+					followerSharedInbox: person.sharedInbox ?? person.endpoints?.sharedInbox ?? null,
+				},
+			);
+
+			await this.cacheService.refreshFollowRelationsFor(exist.id);
+		}
 
 		await this.updateFeatured(exist.id, resolver).catch(err => {
 			// Permanent error implies hidden or inaccessible, which is a normal thing.
diff --git a/packages/backend/src/core/chart/charts/federation.ts b/packages/backend/src/core/chart/charts/federation.ts
index b6db6f5454..4bbb5437cc 100644
--- a/packages/backend/src/core/chart/charts/federation.ts
+++ b/packages/backend/src/core/chart/charts/federation.ts
@@ -44,6 +44,7 @@ export default class FederationChart extends Chart<typeof schema> { // eslint-di
 	}
 
 	protected async tickMinor(): Promise<Partial<KVs<typeof schema>>> {
+		// TODO optimization: replace these with exists()
 		const pubsubSubQuery = this.followingsRepository.createQueryBuilder('f')
 			.select('f.followerHost')
 			.where('f.followerHost IS NOT NULL');
diff --git a/packages/backend/src/core/chart/charts/per-user-following.ts b/packages/backend/src/core/chart/charts/per-user-following.ts
index 588ac638de..8d75a30e9a 100644
--- a/packages/backend/src/core/chart/charts/per-user-following.ts
+++ b/packages/backend/src/core/chart/charts/per-user-following.ts
@@ -15,6 +15,7 @@ import Chart from '../core.js';
 import { ChartLoggerService } from '../ChartLoggerService.js';
 import { name, schema } from './entities/per-user-following.js';
 import type { KVs } from '../core.js';
+import { CacheService } from '@/core/CacheService.js';
 
 /**
  * ユーザーごとのフォローに関するチャート
@@ -31,23 +32,25 @@ export default class PerUserFollowingChart extends Chart<typeof schema> { // esl
 		private appLockService: AppLockService,
 		private userEntityService: UserEntityService,
 		private chartLoggerService: ChartLoggerService,
+		private readonly cacheService: CacheService,
 	) {
 		super(db, (k) => appLockService.getChartInsertLock(k), chartLoggerService.logger, name, schema, true);
 	}
 
 	protected async tickMajor(group: string): Promise<Partial<KVs<typeof schema>>> {
 		const [
-			localFollowingsCount,
-			localFollowersCount,
-			remoteFollowingsCount,
-			remoteFollowersCount,
+			followees,
+			followers,
 		] = await Promise.all([
-			this.followingsRepository.countBy({ followerId: group, followeeHost: IsNull() }),
-			this.followingsRepository.countBy({ followeeId: group, followerHost: IsNull() }),
-			this.followingsRepository.countBy({ followerId: group, followeeHost: Not(IsNull()) }),
-			this.followingsRepository.countBy({ followeeId: group, followerHost: Not(IsNull()) }),
+			this.cacheService.userFollowingsCache.fetch(group).then(fs => Array.from(fs.values())),
+			this.cacheService.userFollowersCache.fetch(group).then(fs => Array.from(fs.values())),
 		]);
 
+		const localFollowingsCount = followees.reduce((sum, f) => sum + (f.followeeHost == null ? 1 : 0), 0);
+		const localFollowersCount = followers.reduce((sum, f) => sum + (f.followerHost == null ? 1 : 0), 0);
+		const remoteFollowingsCount = followees.reduce((sum, f) => sum + (f.followeeHost == null ? 0 : 1), 0);
+		const remoteFollowersCount = followers.reduce((sum, f) => sum + (f.followerHost == null ? 0 : 1), 0);
+
 		return {
 			'local.followings.total': localFollowingsCount,
 			'local.followers.total': localFollowersCount,
diff --git a/packages/backend/src/core/entities/NoteEntityService.ts b/packages/backend/src/core/entities/NoteEntityService.ts
index 3af66b220d..9b447a4064 100644
--- a/packages/backend/src/core/entities/NoteEntityService.ts
+++ b/packages/backend/src/core/entities/NoteEntityService.ts
@@ -11,7 +11,7 @@ import type { Packed } from '@/misc/json-schema.js';
 import { awaitAll } from '@/misc/prelude/await-all.js';
 import type { MiUser } from '@/models/User.js';
 import type { MiNote } from '@/models/Note.js';
-import type { UsersRepository, NotesRepository, FollowingsRepository, PollsRepository, PollVotesRepository, NoteReactionsRepository, ChannelsRepository, MiMeta, MiPollVote, MiPoll, MiChannel } from '@/models/_.js';
+import type { UsersRepository, NotesRepository, FollowingsRepository, PollsRepository, PollVotesRepository, NoteReactionsRepository, ChannelsRepository, MiMeta, MiPollVote, MiPoll, MiChannel, MiFollowing } from '@/models/_.js';
 import { bindThis } from '@/decorators.js';
 import { DebounceLoader } from '@/misc/loader.js';
 import { IdService } from '@/core/IdService.js';
@@ -133,7 +133,7 @@ export class NoteEntityService implements OnModuleInit {
 
 	@bindThis
 	public async hideNote(packedNote: Packed<'Note'>, meId: MiUser['id'] | null, hint?: {
-		myFollowing?: ReadonlyMap<string, { withReplies: boolean }>,
+		myFollowing?: ReadonlyMap<string, unknown>,
 		myBlockers?: ReadonlySet<string>,
 	}): Promise<void> {
 		if (meId === packedNote.userId) return;
@@ -416,7 +416,7 @@ export class NoteEntityService implements OnModuleInit {
 				packedFiles: Map<MiNote['fileIds'][number], Packed<'DriveFile'> | null>;
 				packedUsers: Map<MiUser['id'], Packed<'UserLite'>>;
 				mentionHandles: Record<string, string | undefined>;
-				userFollowings: Map<string, Map<string, { withReplies: boolean }>>;
+				userFollowings: Map<string, Map<string, Omit<MiFollowing, 'isFollowerHibernated'>>>;
 				userBlockers: Map<string, Set<string>>;
 				polls: Map<string, MiPoll>;
 				pollVotes: Map<string, Map<string, MiPollVote[]>>;
@@ -659,9 +659,9 @@ export class NoteEntityService implements OnModuleInit {
 			// mentionHandles
 			this.getUserHandles(Array.from(mentionedUsers)),
 			// userFollowings
-			this.cacheService.getUserFollowings(userIds),
+			this.cacheService.userFollowingsCache.fetchMany(userIds).then(fs => new Map(fs)),
 			// userBlockers
-			this.cacheService.getUserBlockers(userIds),
+			this.cacheService.userBlockedCache.fetchMany(userIds).then(bs => new Map(bs)),
 			// polls
 			this.pollsRepository.findBy({ noteId: In(noteIds) })
 				.then(polls => new Map(polls.map(p => [p.noteId, p]))),
diff --git a/packages/backend/src/core/entities/UserEntityService.ts b/packages/backend/src/core/entities/UserEntityService.ts
index 8ed482af6f..aecbaa7fd5 100644
--- a/packages/backend/src/core/entities/UserEntityService.ts
+++ b/packages/backend/src/core/entities/UserEntityService.ts
@@ -79,7 +79,7 @@ function isRemoteUser(user: MiUser | { host: MiUser['host'] }): boolean {
 
 export type UserRelation = {
 	id: MiUser['id']
-	following: MiFollowing | null,
+	following: Omit<MiFollowing, 'isFollowerHibernated'> | null,
 	isFollowing: boolean
 	isFollowed: boolean
 	hasPendingFollowRequestFromYou: boolean
@@ -197,16 +197,8 @@ export class UserEntityService implements OnModuleInit {
 			memo,
 			mutedInstances,
 		] = await Promise.all([
-			this.followingsRepository.findOneBy({
-				followerId: me,
-				followeeId: target,
-			}),
-			this.followingsRepository.exists({
-				where: {
-					followerId: target,
-					followeeId: me,
-				},
-			}),
+			this.cacheService.userFollowingsCache.fetch(me).then(f => f.get(target) ?? null),
+			this.cacheService.userFollowingsCache.fetch(target).then(f => f.has(me)),
 			this.followRequestsRepository.exists({
 				where: {
 					followerId: me,
@@ -227,8 +219,7 @@ export class UserEntityService implements OnModuleInit {
 				.then(mutings => mutings.has(target)),
 			this.cacheService.renoteMutingsCache.fetch(me)
 				.then(mutings => mutings.has(target)),
-			this.cacheService.userByIdCache.fetch(target, () => this.usersRepository.findOneByOrFail({ id: target }))
-				.then(user => user.host),
+			this.cacheService.findUserById(target).then(u => u.host),
 			this.userMemosRepository.createQueryBuilder('m')
 				.select('m.memo')
 				.where({ userId: me, targetUserId: target })
@@ -271,13 +262,8 @@ export class UserEntityService implements OnModuleInit {
 			memos,
 			mutedInstances,
 		] = await Promise.all([
-			this.followingsRepository.findBy({ followerId: me })
-				.then(f => new Map(f.map(it => [it.followeeId, it]))),
-			this.followingsRepository.createQueryBuilder('f')
-				.select('f.followerId')
-				.where('f.followeeId = :me', { me })
-				.getRawMany<{ f_followerId: string }>()
-				.then(it => it.map(it => it.f_followerId)),
+			this.cacheService.userFollowingsCache.fetch(me),
+			this.cacheService.userFollowersCache.fetch(me),
 			this.followRequestsRepository.createQueryBuilder('f')
 				.select('f.followeeId')
 				.where('f.followerId = :me', { me })
@@ -322,7 +308,7 @@ export class UserEntityService implements OnModuleInit {
 						id: target,
 						following: following,
 						isFollowing: following != null,
-						isFollowed: followees.includes(target),
+						isFollowed: followees.has(target),
 						hasPendingFollowRequestFromYou: followersRequests.includes(target),
 						hasPendingFollowRequestToYou: followeesRequests.includes(target),
 						isBlocking: blockees.has(target),
@@ -354,7 +340,7 @@ export class UserEntityService implements OnModuleInit {
 		return false; // TODO
 	}
 
-	// TODO make redis calls in MULTI?
+	// TODO optimization: make redis calls in MULTI
 	@bindThis
 	public async getNotificationsInfo(userId: MiUser['id']): Promise<{
 		hasUnread: boolean;
@@ -789,11 +775,11 @@ export class UserEntityService implements OnModuleInit {
 			.map(user => user.host)
 			.filter((host): host is string => host != null));
 
-		const _profilesFromUsers: MiUserProfile[] = [];
+		const _profilesFromUsers: [string, MiUserProfile][] = [];
 		const _profilesToFetch: string[] = [];
 		for (const user of _users) {
 			if (user.userProfile) {
-				_profilesFromUsers.push(user.userProfile);
+				_profilesFromUsers.push([user.id, user.userProfile]);
 			} else {
 				_profilesToFetch.push(user.id);
 			}
@@ -803,13 +789,7 @@ export class UserEntityService implements OnModuleInit {
 
 		const [profilesMap, userMemos, userRelations, pinNotes, userIdsByUri, instances, securityKeyCounts, pendingReceivedFollows, pendingSentFollows] = await Promise.all([
 			// profilesMap
-			this.cacheService.getUserProfiles(_profilesToFetch)
-				.then(profiles => {
-					for (const profile of _profilesFromUsers) {
-						profiles.set(profile.userId, profile);
-					}
-					return profiles;
-				}),
+			this.cacheService.userProfileCache.fetchMany(_profilesToFetch).then(profiles => new Map(profiles.concat(_profilesFromUsers))),
 			// userMemos
 			isDetailed && meId ? this.userMemosRepository.findBy({ userId: meId })
 				.then(memos => new Map(memos.map(memo => [memo.targetUserId, memo.memo]))) : new Map(),
@@ -857,7 +837,7 @@ export class UserEntityService implements OnModuleInit {
 				.groupBy('key.userId')
 				.getRawMany<{ userId: string, userCount: number }>()
 				.then(counts => new Map(counts.map(c => [c.userId, c.userCount]))) : new Map(),
-			// TODO check query performance
+			// TODO optimization: cache follow requests
 			// pendingReceivedFollows
 			isDetailedAndMe ? this.followRequestsRepository.createQueryBuilder('req')
 				.select('req.followeeId', 'followeeId')
diff --git a/packages/backend/src/misc/QuantumKVCache.ts b/packages/backend/src/misc/QuantumKVCache.ts
index 6b36789f5e..b96937d6f2 100644
--- a/packages/backend/src/misc/QuantumKVCache.ts
+++ b/packages/backend/src/misc/QuantumKVCache.ts
@@ -21,18 +21,18 @@ export interface QuantumKVOpts<T> {
 	fetcher: (key: string, cache: QuantumKVCache<T>) => T | Promise<T>;
 
 	/**
-	 * Optional callback when a value is created or changed in the cache, either locally or elsewhere in the cluster.
-	 * This is called *after* the cache state is updated.
+	 * Optional callback to fetch the value for multiple keys that weren't found in the cache.
 	 * May be synchronous or async.
+	 * If not provided, then the implementation will fall back on repeated calls to fetcher().
 	 */
-	onSet?: (key: string, cache: QuantumKVCache<T>) => void | Promise<void>;
+	bulkFetcher?: (keys: string[], cache: QuantumKVCache<T>) => Iterable<[key: string, value: T]> | Promise<Iterable<[key: string, value: T]>>;
 
 	/**
-	 * Optional callback when a value is deleted from the cache, either locally or elsewhere in the cluster.
+	 * Optional callback when one or more values are changed (created, updated, or deleted) in the cache, either locally or elsewhere in the cluster.
 	 * This is called *after* the cache state is updated.
-	 * May be synchronous or async.
+	 * Implementations may be synchronous or async.
 	 */
-	onDelete?: (key: string, cache: QuantumKVCache<T>) => void | Promise<void>;
+	onChanged?: (keys: string[], cache: QuantumKVCache<T>) => void | Promise<void>;
 }
 
 /**
@@ -44,8 +44,8 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 	private readonly memoryCache: MemoryKVCache<T>;
 
 	public readonly fetcher: QuantumKVOpts<T>['fetcher'];
-	public readonly onSet: QuantumKVOpts<T>['onSet'];
-	public readonly onDelete: QuantumKVOpts<T>['onDelete'];
+	public readonly bulkFetcher: QuantumKVOpts<T>['bulkFetcher'];
+	public readonly onChanged: QuantumKVOpts<T>['onChanged'];
 
 	/**
 	 * @param internalEventService Service bus to synchronize events.
@@ -59,8 +59,8 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 	) {
 		this.memoryCache = new MemoryKVCache(opts.lifetime);
 		this.fetcher = opts.fetcher;
-		this.onSet = opts.onSet;
-		this.onDelete = opts.onDelete;
+		this.bulkFetcher = opts.bulkFetcher;
+		this.onChanged = opts.onChanged;
 
 		this.internalEventService.on('quantumCacheUpdated', this.onQuantumCacheUpdated, {
 			// Ignore our own events, otherwise we'll immediately erase any set value.
@@ -122,10 +122,10 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 
 		this.memoryCache.set(key, value);
 
-		await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, op: 's', keys: [key] });
+		await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, keys: [key] });
 
-		if (this.onSet) {
-			await this.onSet(key, this);
+		if (this.onChanged) {
+			await this.onChanged([key], this);
 		}
 	}
 
@@ -146,12 +146,10 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 		}
 
 		if (changedKeys.length > 0) {
-			await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, op: 's', keys: changedKeys });
+			await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, keys: changedKeys });
 
-			if (this.onSet) {
-				for (const key of changedKeys) {
-					await this.onSet(key, this);
-				}
+			if (this.onChanged) {
+				await this.onChanged(changedKeys, this);
 			}
 		}
 	}
@@ -180,6 +178,7 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 
 	/**
 	 * Gets a value from the local memory cache, or returns undefined if not found.
+	 * Returns cached data only - does not make any fetches.
 	 */
 	@bindThis
 	public get(key: string): T | undefined {
@@ -187,6 +186,19 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 	}
 
 	/**
+	 * Gets multiple values from the local memory cache; returning undefined for any missing keys.
+	 * Returns cached data only - does not make any fetches.
+	 */
+	@bindThis
+	public getMany(keys: Iterable<string>): [key: string, value: T | undefined][] {
+		const results: [key: string, value: T | undefined][] = [];
+		for (const key of keys) {
+			results.push([key, this.get(key)]);
+		}
+		return results;
+	}
+
+	/**
 	 * Gets or fetches a value from the cache.
 	 * Fires an onSet event, but does not emit an update event to other processes.
 	 */
@@ -197,14 +209,50 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 			value = await this.fetcher(key, this);
 			this.memoryCache.set(key, value);
 
-			if (this.onSet) {
-				await this.onSet(key, this);
+			if (this.onChanged) {
+				await this.onChanged([key], this);
 			}
 		}
 		return value;
 	}
 
 	/**
+	 * Gets or fetches multiple values from the cache.
+	 * Fires onSet events, but does not emit any update events to other processes.
+	 */
+	@bindThis
+	public async fetchMany(keys: Iterable<string>): Promise<[key: string, value: T][]> {
+		const results: [key: string, value: T][] = [];
+		const toFetch: string[] = [];
+
+		// Spliterate into cached results / uncached keys.
+		for (const key of keys) {
+			const fromCache = this.get(key);
+			if (fromCache) {
+				results.push([key, fromCache]);
+			} else {
+				toFetch.push(key);
+			}
+		}
+
+		// Fetch any uncached keys
+		if (toFetch.length > 0) {
+			const fetched = await this.bulkFetch(toFetch);
+
+			// Add to cache and return set
+			this.addMany(fetched);
+			results.push(...fetched);
+
+			// Emit event
+			if (this.onChanged) {
+				await this.onChanged(toFetch, this);
+			}
+		}
+
+		return results;
+	}
+
+	/**
 	 * Returns true is a key exists in memory.
 	 * This applies to the local subset view, not the cross-cluster cache state.
 	 */
@@ -221,10 +269,10 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 	public async delete(key: string): Promise<void> {
 		this.memoryCache.delete(key);
 
-		await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, op: 'd', keys: [key] });
+		await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, keys: [key] });
 
-		if (this.onDelete) {
-			await this.onDelete(key, this);
+		if (this.onChanged) {
+			await this.onChanged([key], this);
 		}
 	}
 	/**
@@ -233,21 +281,22 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 	 * Skips if the input is empty.
 	 */
 	@bindThis
-	public async deleteMany(keys: string[]): Promise<void> {
-		if (keys.length === 0) {
-			return;
-		}
+	public async deleteMany(keys: Iterable<string>): Promise<void> {
+		const deleted: string[] = [];
 
 		for (const key of keys) {
 			this.memoryCache.delete(key);
+			deleted.push(key);
 		}
 
-		await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, op: 'd', keys });
+		if (deleted.length === 0) {
+			return;
+		}
 
-		if (this.onDelete) {
-			for (const key of keys) {
-				await this.onDelete(key, this);
-			}
+		await this.internalEventService.emit('quantumCacheUpdated', { name: this.name, keys: deleted });
+
+		if (this.onChanged) {
+			await this.onChanged(deleted, this);
 		}
 	}
 
@@ -262,6 +311,13 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 		return value;
 	}
 
+	@bindThis
+	public async refreshMany(keys: Iterable<string>): Promise<[key: string, value: T][]> {
+		const values = await this.bulkFetch(keys);
+		await this.setMany(values);
+		return values;
+	}
+
 	/**
 	 * Erases all entries from the local memory cache.
 	 * Does not send any events or update other processes.
@@ -292,18 +348,29 @@ export class QuantumKVCache<T> implements Iterable<[key: string, value: T]> {
 	}
 
 	@bindThis
+	private async bulkFetch(keys: Iterable<string>): Promise<[key: string, value: T][]> {
+		if (this.bulkFetcher) {
+			const results = await this.bulkFetcher(Array.from(keys), this);
+			return Array.from(results);
+		}
+
+		const results: [key: string, value: T][] = [];
+		for (const key of keys) {
+			const value = await this.fetcher(key, this);
+			results.push([key, value]);
+		}
+		return results;
+	}
+
+	@bindThis
 	private async onQuantumCacheUpdated(data: InternalEventTypes['quantumCacheUpdated']): Promise<void> {
 		if (data.name === this.name) {
 			for (const key of data.keys) {
 				this.memoryCache.delete(key);
+			}
 
-				if (data.op === 's' && this.onSet) {
-					await this.onSet(key, this);
-				}
-
-				if (data.op === 'd' && this.onDelete) {
-					await this.onDelete(key, this);
-				}
+			if (this.onChanged) {
+				await this.onChanged(data.keys, this);
 			}
 		}
 	}
diff --git a/packages/backend/src/misc/cache.ts b/packages/backend/src/misc/cache.ts
index 932c0b409a..666e684c1c 100644
--- a/packages/backend/src/misc/cache.ts
+++ b/packages/backend/src/misc/cache.ts
@@ -5,8 +5,6 @@
 
 import * as Redis from 'ioredis';
 import { bindThis } from '@/decorators.js';
-import { InternalEventService } from '@/core/InternalEventService.js';
-import { InternalEventTypes } from '@/core/GlobalEventService.js';
 
 export class RedisKVCache<T> {
 	private readonly lifetime: number;
@@ -120,9 +118,9 @@ export class RedisKVCache<T> {
 export class RedisSingleCache<T> {
 	private readonly lifetime: number;
 	private readonly memoryCache: MemorySingleCache<T>;
-	private readonly fetcher: () => Promise<T>;
-	private readonly toRedisConverter: (value: T) => string;
-	private readonly fromRedisConverter: (value: string) => T | undefined;
+	public readonly fetcher: () => Promise<T>;
+	public readonly toRedisConverter: (value: T) => string;
+	public readonly fromRedisConverter: (value: string) => T | undefined;
 
 	constructor(
 		private redisClient: Redis.Redis,
@@ -245,6 +243,16 @@ export class MemoryKVCache<T> {
 		return cached.value;
 	}
 
+	public has(key: string): boolean {
+		const cached = this.cache.get(key);
+		if (cached == null) return false;
+		if ((Date.now() - cached.date) > this.lifetime) {
+			this.cache.delete(key);
+			return false;
+		}
+		return true;
+	}
+
 	@bindThis
 	public delete(key: string): void {
 		this.cache.delete(key);
diff --git a/packages/backend/src/queue/processors/DeleteAccountProcessorService.ts b/packages/backend/src/queue/processors/DeleteAccountProcessorService.ts
index 6a1a8bcc66..5bf64e4f04 100644
--- a/packages/backend/src/queue/processors/DeleteAccountProcessorService.ts
+++ b/packages/backend/src/queue/processors/DeleteAccountProcessorService.ts
@@ -18,6 +18,7 @@ import { SearchService } from '@/core/SearchService.js';
 import { ApLogService } from '@/core/ApLogService.js';
 import { ReactionService } from '@/core/ReactionService.js';
 import { QueueService } from '@/core/QueueService.js';
+import { CacheService } from '@/core/CacheService.js';
 import { QueueLoggerService } from '../QueueLoggerService.js';
 import type * as Bull from 'bullmq';
 import type { DbUserDeleteJobData } from '../types.js';
@@ -94,6 +95,7 @@ export class DeleteAccountProcessorService {
 		private searchService: SearchService,
 		private reactionService: ReactionService,
 		private readonly apLogService: ApLogService,
+		private readonly cacheService: CacheService,
 	) {
 		this.logger = this.queueLoggerService.logger.createSubLogger('delete-account');
 	}
@@ -140,6 +142,22 @@ export class DeleteAccountProcessorService {
 		}
 
 		{ // Delete user relations
+			await this.cacheService.refreshFollowRelationsFor(user.id);
+			await this.cacheService.userFollowingsCache.delete(user.id);
+			await this.cacheService.userFollowingsCache.delete(user.id);
+			await this.cacheService.userBlockingCache.delete(user.id);
+			await this.cacheService.userBlockedCache.delete(user.id);
+			await this.cacheService.userMutingsCache.delete(user.id);
+			await this.cacheService.userMutingsCache.delete(user.id);
+			await this.cacheService.hibernatedUserCache.delete(user.id);
+			await this.cacheService.renoteMutingsCache.delete(user.id);
+			await this.cacheService.userProfileCache.delete(user.id);
+			this.cacheService.userByIdCache.delete(user.id);
+			this.cacheService.localUserByIdCache.delete(user.id);
+			if (user.token) {
+				this.cacheService.localUserByNativeTokenCache.delete(user.token);
+			}
+
 			await this.followingsRepository.delete({
 				followerId: user.id,
 			});
diff --git a/packages/backend/src/server/api/endpoints/following/delete.ts b/packages/backend/src/server/api/endpoints/following/delete.ts
index ba146b6703..442352a4d2 100644
--- a/packages/backend/src/server/api/endpoints/following/delete.ts
+++ b/packages/backend/src/server/api/endpoints/following/delete.ts
@@ -12,6 +12,7 @@ import { UserFollowingService } from '@/core/UserFollowingService.js';
 import { DI } from '@/di-symbols.js';
 import { GetterService } from '@/server/api/GetterService.js';
 import { ApiError } from '../../error.js';
+import { CacheService } from '@/core/CacheService.js';
 
 export const meta = {
 	tags: ['following', 'users'],
@@ -69,6 +70,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private userEntityService: UserEntityService,
 		private getterService: GetterService,
 		private userFollowingService: UserFollowingService,
+		private readonly cacheService: CacheService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			const follower = me;
@@ -85,12 +87,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			});
 
 			// Check not following
-			const exist = await this.followingsRepository.exists({
-				where: {
-					followerId: follower.id,
-					followeeId: followee.id,
-				},
-			});
+			const exist = await this.cacheService.userFollowingsCache.fetch(follower.id).then(f => f.has(followee.id));
 
 			if (!exist) {
 				throw new ApiError(meta.errors.notFollowing);
diff --git a/packages/backend/src/server/api/endpoints/following/invalidate.ts b/packages/backend/src/server/api/endpoints/following/invalidate.ts
index b45d21410b..3809bf29b0 100644
--- a/packages/backend/src/server/api/endpoints/following/invalidate.ts
+++ b/packages/backend/src/server/api/endpoints/following/invalidate.ts
@@ -11,6 +11,7 @@ import { UserEntityService } from '@/core/entities/UserEntityService.js';
 import { UserFollowingService } from '@/core/UserFollowingService.js';
 import { DI } from '@/di-symbols.js';
 import { GetterService } from '@/server/api/GetterService.js';
+import { CacheService } from '@/core/CacheService.js';
 import { ApiError } from '../../error.js';
 
 export const meta = {
@@ -69,6 +70,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private userEntityService: UserEntityService,
 		private getterService: GetterService,
 		private userFollowingService: UserFollowingService,
+		private readonly cacheService: CacheService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			const followee = me;
@@ -85,12 +87,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			});
 
 			// Check not following
-			const exist = await this.followingsRepository.findOneBy({
-				followerId: follower.id,
-				followeeId: followee.id,
-			});
+			const isFollowing = await this.cacheService.userFollowingsCache.fetch(follower.id).then(f => f.has(followee.id));
 
-			if (exist == null) {
+			if (!isFollowing) {
 				throw new ApiError(meta.errors.notFollowing);
 			}
 
diff --git a/packages/backend/src/server/api/endpoints/following/update-all.ts b/packages/backend/src/server/api/endpoints/following/update-all.ts
index c953feb393..a02b51cc79 100644
--- a/packages/backend/src/server/api/endpoints/following/update-all.ts
+++ b/packages/backend/src/server/api/endpoints/following/update-all.ts
@@ -12,6 +12,7 @@ import { UserFollowingService } from '@/core/UserFollowingService.js';
 import { DI } from '@/di-symbols.js';
 import { GetterService } from '@/server/api/GetterService.js';
 import { ApiError } from '../../error.js';
+import { CacheService } from '@/core/CacheService.js';
 
 export const meta = {
 	tags: ['following', 'users'],
@@ -39,6 +40,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 	constructor(
 		@Inject(DI.followingsRepository)
 		private followingsRepository: FollowingsRepository,
+		private readonly cacheService: CacheService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			await this.followingsRepository.update({
@@ -48,6 +50,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				withReplies: ps.withReplies != null ? ps.withReplies : undefined,
 			});
 
+			await this.cacheService.refreshFollowRelationsFor(me.id);
+
 			return;
 		});
 	}
diff --git a/packages/backend/src/server/api/endpoints/following/update.ts b/packages/backend/src/server/api/endpoints/following/update.ts
index d62cf210ed..f4ca21856f 100644
--- a/packages/backend/src/server/api/endpoints/following/update.ts
+++ b/packages/backend/src/server/api/endpoints/following/update.ts
@@ -11,6 +11,7 @@ import { UserEntityService } from '@/core/entities/UserEntityService.js';
 import { UserFollowingService } from '@/core/UserFollowingService.js';
 import { DI } from '@/di-symbols.js';
 import { GetterService } from '@/server/api/GetterService.js';
+import { CacheService } from '@/core/CacheService.js';
 import { ApiError } from '../../error.js';
 
 export const meta = {
@@ -71,6 +72,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private userEntityService: UserEntityService,
 		private getterService: GetterService,
 		private userFollowingService: UserFollowingService,
+		private readonly cacheService: CacheService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			const follower = me;
@@ -87,10 +89,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			});
 
 			// Check not following
-			const exist = await this.followingsRepository.findOneBy({
-				followerId: follower.id,
-				followeeId: followee.id,
-			});
+			const exist = await this.cacheService.userFollowingsCache.fetch(follower.id).then(f => f.get(followee.id));
 
 			if (exist == null) {
 				throw new ApiError(meta.errors.notFollowing);
@@ -103,6 +102,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				withReplies: ps.withReplies != null ? ps.withReplies : undefined,
 			});
 
+			await this.cacheService.refreshFollowRelationsFor(follower.id);
+
 			return await this.userEntityService.pack(follower.id, me);
 		});
 	}
diff --git a/packages/backend/src/server/api/endpoints/users/followers.ts b/packages/backend/src/server/api/endpoints/users/followers.ts
index c1617e14e5..82ce282bfc 100644
--- a/packages/backend/src/server/api/endpoints/users/followers.ts
+++ b/packages/backend/src/server/api/endpoints/users/followers.ts
@@ -12,6 +12,7 @@ import { FollowingEntityService } from '@/core/entities/FollowingEntityService.j
 import { UtilityService } from '@/core/UtilityService.js';
 import { DI } from '@/di-symbols.js';
 import { RoleService } from '@/core/RoleService.js';
+import { CacheService } from '@/core/CacheService.js';
 import { ApiError } from '../../error.js';
 
 export const meta = {
@@ -89,6 +90,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private followingEntityService: FollowingEntityService,
 		private queryService: QueryService,
 		private roleService: RoleService,
+		private readonly cacheService: CacheService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			const user = await this.usersRepository.findOneBy(ps.userId != null
@@ -110,12 +112,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 					if (me == null) {
 						throw new ApiError(meta.errors.forbidden);
 					} else if (me.id !== user.id) {
-						const isFollowing = await this.followingsRepository.exists({
-							where: {
-								followeeId: user.id,
-								followerId: me.id,
-							},
-						});
+						const isFollowing = await this.cacheService.userFollowingsCache.fetch(me.id).then(f => f.has(user.id));
 						if (!isFollowing) {
 							throw new ApiError(meta.errors.forbidden);
 						}
diff --git a/packages/backend/src/server/api/endpoints/users/following.ts b/packages/backend/src/server/api/endpoints/users/following.ts
index c292c6d6a3..80f0b0c484 100644
--- a/packages/backend/src/server/api/endpoints/users/following.ts
+++ b/packages/backend/src/server/api/endpoints/users/following.ts
@@ -13,6 +13,7 @@ import { FollowingEntityService } from '@/core/entities/FollowingEntityService.j
 import { UtilityService } from '@/core/UtilityService.js';
 import { DI } from '@/di-symbols.js';
 import { RoleService } from '@/core/RoleService.js';
+import { CacheService } from '@/core/CacheService.js';
 import { ApiError } from '../../error.js';
 
 export const meta = {
@@ -98,6 +99,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private followingEntityService: FollowingEntityService,
 		private queryService: QueryService,
 		private roleService: RoleService,
+		private readonly cacheService: CacheService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			const user = await this.usersRepository.findOneBy(ps.userId != null
@@ -119,12 +121,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 					if (me == null) {
 						throw new ApiError(meta.errors.forbidden);
 					} else if (me.id !== user.id) {
-						const isFollowing = await this.followingsRepository.exists({
-							where: {
-								followeeId: user.id,
-								followerId: me.id,
-							},
-						});
+						const isFollowing = await this.cacheService.userFollowingsCache.fetch(me.id).then(f => f.has(user.id));
 						if (!isFollowing) {
 							throw new ApiError(meta.errors.forbidden);
 						}
diff --git a/packages/backend/src/server/api/endpoints/users/recommendation.ts b/packages/backend/src/server/api/endpoints/users/recommendation.ts
index 642d788459..52dd2197b2 100644
--- a/packages/backend/src/server/api/endpoints/users/recommendation.ts
+++ b/packages/backend/src/server/api/endpoints/users/recommendation.ts
@@ -71,6 +71,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			this.queryService.generateBlockQueryForUsers(query, me);
 			this.queryService.generateBlockedUserQueryForNotes(query, me);
 
+			// TODO optimization: replace with exists()
 			const followingQuery = this.followingsRepository.createQueryBuilder('following')
 				.select('following.followeeId')
 				.where('following.followerId = :followerId', { followerId: me.id });
diff --git a/packages/backend/src/server/api/stream/Connection.ts b/packages/backend/src/server/api/stream/Connection.ts
index 21437850d3..0ee7078eb2 100644
--- a/packages/backend/src/server/api/stream/Connection.ts
+++ b/packages/backend/src/server/api/stream/Connection.ts
@@ -36,7 +36,7 @@ export default class Connection {
 	private channels = new Map<string, Channel>();
 	private subscribingNotes = new Map<string, number>();
 	public userProfile: MiUserProfile | null = null;
-	public following: Map<string, { withReplies: boolean }> = new Map();
+	public following: Map<string, Omit<MiFollowing, 'isFollowerHibernated'>> = new Map();
 	public followingChannels: Set<string> = new Set();
 	public userIdsWhoMeMuting: Set<string> = new Set();
 	public userIdsWhoBlockingMe: Set<string> = new Set();
diff --git a/packages/backend/test/misc/noOpCaches.ts b/packages/backend/test/misc/noOpCaches.ts
index 40c5d2dc65..f3cc1e2ba2 100644
--- a/packages/backend/test/misc/noOpCaches.ts
+++ b/packages/backend/test/misc/noOpCaches.ts
@@ -6,13 +6,14 @@
 import * as Redis from 'ioredis';
 import { Inject } from '@nestjs/common';
 import { FakeInternalEventService } from './FakeInternalEventService.js';
-import type { BlockingsRepository, FollowingsRepository, MiUser, MiUserProfile, MutingsRepository, RenoteMutingsRepository, UserProfilesRepository, UsersRepository } from '@/models/_.js';
+import type { BlockingsRepository, FollowingsRepository, MiUser, MutingsRepository, RenoteMutingsRepository, UserProfilesRepository, UsersRepository } from '@/models/_.js';
 import type { MiLocalUser } from '@/models/User.js';
 import { MemoryKVCache, MemorySingleCache, RedisKVCache, RedisSingleCache } from '@/misc/cache.js';
 import { QuantumKVCache, QuantumKVOpts } from '@/misc/QuantumKVCache.js';
-import { CacheService, CachedTranslationEntity, FollowStats } from '@/core/CacheService.js';
+import { CacheService, FollowStats } from '@/core/CacheService.js';
 import { DI } from '@/di-symbols.js';
 import { UserEntityService } from '@/core/entities/UserEntityService.js';
+import { InternalEventService } from '@/core/InternalEventService.js';
 
 export function noOpRedis() {
 	return {
@@ -76,55 +77,16 @@ export class NoOpCacheService extends CacheService {
 		this.localUserByNativeTokenCache = new NoOpMemoryKVCache<MiLocalUser | null>();
 		this.localUserByIdCache = new NoOpMemoryKVCache<MiLocalUser>();
 		this.uriPersonCache = new NoOpMemoryKVCache<MiUser | null>();
-		this.userProfileCache = new NoOpQuantumKVCache<MiUserProfile>({
-			internalEventService: fakeInternalEventService,
-			fetcher: this.userProfileCache.fetcher,
-			onSet: this.userProfileCache.onSet,
-			onDelete: this.userProfileCache.onDelete,
-		});
-		this.userMutingsCache = new NoOpQuantumKVCache<Set<string>>({
-			internalEventService: fakeInternalEventService,
-			fetcher: this.userMutingsCache.fetcher,
-			onSet: this.userMutingsCache.onSet,
-			onDelete: this.userMutingsCache.onDelete,
-		});
-		this.userBlockingCache = new NoOpQuantumKVCache<Set<string>>({
-			internalEventService: fakeInternalEventService,
-			fetcher: this.userBlockingCache.fetcher,
-			onSet: this.userBlockingCache.onSet,
-			onDelete: this.userBlockingCache.onDelete,
-		});
-		this.userBlockedCache = new NoOpQuantumKVCache<Set<string>>({
-			internalEventService: fakeInternalEventService,
-			fetcher: this.userBlockedCache.fetcher,
-			onSet: this.userBlockedCache.onSet,
-			onDelete: this.userBlockedCache.onDelete,
-		});
-		this.renoteMutingsCache = new NoOpQuantumKVCache<Set<string>>({
-			internalEventService: fakeInternalEventService,
-			fetcher: this.renoteMutingsCache.fetcher,
-			onSet: this.renoteMutingsCache.onSet,
-			onDelete: this.renoteMutingsCache.onDelete,
-		});
-		this.userFollowingsCache = new NoOpQuantumKVCache<Map<string, { withReplies: boolean }>>({
-			internalEventService: fakeInternalEventService,
-			fetcher: this.userFollowingsCache.fetcher,
-			onSet: this.userFollowingsCache.onSet,
-			onDelete: this.userFollowingsCache.onDelete,
-		});
-		this.userFollowersCache = new NoOpQuantumKVCache<Set<string>>({
-			internalEventService: fakeInternalEventService,
-			fetcher: this.userFollowersCache.fetcher,
-			onSet: this.userFollowersCache.onSet,
-			onDelete: this.userFollowersCache.onDelete,
-		});
+		this.userProfileCache = NoOpQuantumKVCache.copy(this.userProfileCache, fakeInternalEventService);
+		this.userMutingsCache = NoOpQuantumKVCache.copy(this.userMutingsCache, fakeInternalEventService);
+		this.userBlockingCache = NoOpQuantumKVCache.copy(this.userBlockingCache, fakeInternalEventService);
+		this.userBlockedCache = NoOpQuantumKVCache.copy(this.userBlockedCache, fakeInternalEventService);
+		this.renoteMutingsCache = NoOpQuantumKVCache.copy(this.renoteMutingsCache, fakeInternalEventService);
+		this.userFollowingsCache = NoOpQuantumKVCache.copy(this.userFollowingsCache, fakeInternalEventService);
+		this.userFollowersCache = NoOpQuantumKVCache.copy(this.userFollowersCache, fakeInternalEventService);
+		this.hibernatedUserCache = NoOpQuantumKVCache.copy(this.hibernatedUserCache, fakeInternalEventService);
 		this.userFollowStatsCache = new NoOpMemoryKVCache<FollowStats>();
-		this.translationsCache = new NoOpRedisKVCache<CachedTranslationEntity>({
-			redis: fakeRedis,
-			fetcher: this.translationsCache.fetcher,
-			toRedisConverter: this.translationsCache.toRedisConverter,
-			fromRedisConverter: this.translationsCache.fromRedisConverter,
-		});
+		this.translationsCache = NoOpRedisKVCache.copy(this.translationsCache, fakeRedis);
 	}
 }
 
@@ -159,17 +121,26 @@ export class NoOpRedisKVCache<T> extends RedisKVCache<T> {
 			},
 		);
 	}
+
+	public static copy<T>(cache: RedisKVCache<T>, redis?: Redis.Redis): NoOpRedisKVCache<T> {
+		return new NoOpRedisKVCache<T>({
+			redis,
+			fetcher: cache.fetcher,
+			toRedisConverter: cache.toRedisConverter,
+			fromRedisConverter: cache.fromRedisConverter,
+		});
+	}
 }
 
 export class NoOpRedisSingleCache<T> extends RedisSingleCache<T> {
 	constructor(opts?: {
-		fakeRedis?: Redis.Redis;
+		redis?: Redis.Redis;
 		fetcher?: RedisSingleCache<T>['fetcher'];
 		toRedisConverter?: RedisSingleCache<T>['toRedisConverter'];
 		fromRedisConverter?: RedisSingleCache<T>['fromRedisConverter'];
 	}) {
 		super(
-			opts?.fakeRedis ?? noOpRedis(),
+			opts?.redis ?? noOpRedis(),
 			'no-op',
 			{
 				lifetime: -1,
@@ -180,24 +151,37 @@ export class NoOpRedisSingleCache<T> extends RedisSingleCache<T> {
 			},
 		);
 	}
+
+	public static copy<T>(cache: RedisSingleCache<T>, redis?: Redis.Redis): NoOpRedisSingleCache<T> {
+		return new NoOpRedisSingleCache<T>({
+			redis,
+			fetcher: cache.fetcher,
+			toRedisConverter: cache.toRedisConverter,
+			fromRedisConverter: cache.fromRedisConverter,
+		});
+	}
 }
 
 export class NoOpQuantumKVCache<T> extends QuantumKVCache<T> {
-	constructor(opts: {
-		internalEventService?: FakeInternalEventService,
-		fetcher: QuantumKVOpts<T>['fetcher'],
-		onSet?: QuantumKVOpts<T>['onSet'],
-		onDelete?: QuantumKVOpts<T>['onDelete'],
+	constructor(opts: Omit<QuantumKVOpts<T>, 'lifetime'> & {
+		internalEventService?: InternalEventService,
 	}) {
 		super(
 			opts.internalEventService ?? new FakeInternalEventService(),
 			'no-op',
 			{
+				...opts,
 				lifetime: -1,
-				fetcher: opts.fetcher,
-				onSet: opts.onSet,
-				onDelete: opts.onDelete,
 			},
 		);
 	}
+
+	public static copy<T>(cache: QuantumKVCache<T>, internalEventService?: InternalEventService): NoOpQuantumKVCache<T> {
+		return new NoOpQuantumKVCache<T>({
+			internalEventService,
+			fetcher: cache.fetcher,
+			bulkFetcher: cache.bulkFetcher,
+			onChanged: cache.onChanged,
+		});
+	}
 }
diff --git a/packages/backend/test/unit/misc/QuantumKVCache.ts b/packages/backend/test/unit/misc/QuantumKVCache.ts
index 72997494ce..92792171be 100644
--- a/packages/backend/test/unit/misc/QuantumKVCache.ts
+++ b/packages/backend/test/unit/misc/QuantumKVCache.ts
@@ -73,19 +73,19 @@ describe(QuantumKVCache, () => {
 
 		await cache.set('foo', 'bar');
 
-		expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', op: 's', keys: ['foo'] }]]);
+		expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['foo'] }]]);
 	});
 
-	it('should call onSet when storing', async () => {
-		const fakeOnSet = jest.fn(() => Promise.resolve());
+	it('should call onChanged when storing', async () => {
+		const fakeOnChanged = jest.fn(() => Promise.resolve());
 		const cache = makeCache<string>({
 			name: 'fake',
-			onSet: fakeOnSet,
+			onChanged: fakeOnChanged,
 		});
 
 		await cache.set('foo', 'bar');
 
-		expect(fakeOnSet).toHaveBeenCalledWith('foo', cache);
+		expect(fakeOnChanged).toHaveBeenCalledWith(['foo'], cache);
 	});
 
 	it('should not emit event when storing unchanged value', async () => {
@@ -97,17 +97,17 @@ describe(QuantumKVCache, () => {
 		expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(1);
 	});
 
-	it('should not call onSet when storing unchanged value', async () => {
-		const fakeOnSet = jest.fn(() => Promise.resolve());
+	it('should not call onChanged when storing unchanged value', async () => {
+		const fakeOnChanged = jest.fn(() => Promise.resolve());
 		const cache = makeCache<string>({
 			name: 'fake',
-			onSet: fakeOnSet,
+			onChanged: fakeOnChanged,
 		});
 
 		await cache.set('foo', 'bar');
 		await cache.set('foo', 'bar');
 
-		expect(fakeOnSet).toHaveBeenCalledTimes(1);
+		expect(fakeOnChanged).toHaveBeenCalledTimes(1);
 	});
 
 	it('should fetch an unknown value', async () => {
@@ -133,17 +133,17 @@ describe(QuantumKVCache, () => {
 		expect(result).toBe(true);
 	});
 
-	it('should call onSet when fetching', async () => {
-		const fakeOnSet = jest.fn(() => Promise.resolve());
+	it('should call onChanged when fetching', async () => {
+		const fakeOnChanged = jest.fn(() => Promise.resolve());
 		const cache = makeCache<string>({
 			name: 'fake',
 			fetcher: key => `value#${key}`,
-			onSet: fakeOnSet,
+			onChanged: fakeOnChanged,
 		});
 
 		await cache.fetch('foo');
 
-		expect(fakeOnSet).toHaveBeenCalledWith('foo', cache);
+		expect(fakeOnChanged).toHaveBeenCalledWith(['foo'], cache);
 	});
 
 	it('should not emit event when fetching', async () => {
@@ -154,7 +154,7 @@ describe(QuantumKVCache, () => {
 
 		await cache.fetch('foo');
 
-		expect(fakeInternalEventService._calls).not.toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', op: 's', keys: ['foo'] }]]);
+		expect(fakeInternalEventService._calls).not.toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['foo'] }]]);
 	});
 
 	it('should delete from memory cache', async () => {
@@ -167,17 +167,17 @@ describe(QuantumKVCache, () => {
 		expect(result).toBe(false);
 	});
 
-	it('should call onDelete when deleting', async () => {
-		const fakeOnDelete = jest.fn(() => Promise.resolve());
+	it('should call onChanged when deleting', async () => {
+		const fakeOnChanged = jest.fn(() => Promise.resolve());
 		const cache = makeCache<string>({
 			name: 'fake',
-			onDelete: fakeOnDelete,
+			onChanged: fakeOnChanged,
 		});
 
 		await cache.set('foo', 'bar');
 		await cache.delete('foo');
 
-		expect(fakeOnDelete).toHaveBeenCalledWith('foo', cache);
+		expect(fakeOnChanged).toHaveBeenCalledWith(['foo'], cache);
 	});
 
 	it('should emit event when deleting', async () => {
@@ -186,52 +186,52 @@ describe(QuantumKVCache, () => {
 		await cache.set('foo', 'bar');
 		await cache.delete('foo');
 
-		expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', op: 'd', keys: ['foo'] }]]);
+		expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['foo'] }]]);
 	});
 
 	it('should delete when receiving set event', async () => {
 		const cache = makeCache<string>({ name: 'fake' });
 		await cache.set('foo', 'bar');
 
-		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', op: 's', keys: ['foo'] });
+		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', keys: ['foo'] });
 
 		const result = cache.has('foo');
 		expect(result).toBe(false);
 	});
 
-	it('should call onSet when receiving set event', async () => {
-		const fakeOnSet = jest.fn(() => Promise.resolve());
+	it('should call onChanged when receiving set event', async () => {
+		const fakeOnChanged = jest.fn(() => Promise.resolve());
 		const cache = makeCache<string>({
 			name: 'fake',
-			onSet: fakeOnSet,
+			onChanged: fakeOnChanged,
 		});
 
-		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', op: 's', keys: ['foo'] });
+		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', keys: ['foo'] });
 
-		expect(fakeOnSet).toHaveBeenCalledWith('foo', cache);
+		expect(fakeOnChanged).toHaveBeenCalledWith(['foo'], cache);
 	});
 
 	it('should delete when receiving delete event', async () => {
 		const cache = makeCache<string>({ name: 'fake' });
 		await cache.set('foo', 'bar');
 
-		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', op: 'd', keys: ['foo'] });
+		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', keys: ['foo'] });
 
 		const result = cache.has('foo');
 		expect(result).toBe(false);
 	});
 
-	it('should call onDelete when receiving delete event', async () => {
-		const fakeOnDelete = jest.fn(() => Promise.resolve());
+	it('should call onChanged when receiving delete event', async () => {
+		const fakeOnChanged = jest.fn(() => Promise.resolve());
 		const cache = makeCache<string>({
 			name: 'fake',
-			onDelete: fakeOnDelete,
+			onChanged: fakeOnChanged,
 		});
 		await cache.set('foo', 'bar');
 
-		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', op: 'd', keys: ['foo'] });
+		await fakeInternalEventService._emitRedis('quantumCacheUpdated', { name: 'fake', keys: ['foo'] });
 
-		expect(fakeOnDelete).toHaveBeenCalledWith('foo', cache);
+		expect(fakeOnChanged).toHaveBeenCalledWith(['foo'], cache);
 	});
 
 	describe('get', () => {
@@ -269,40 +269,243 @@ describe(QuantumKVCache, () => {
 
 			await cache.setMany([['foo', 'bar'], ['alpha', 'omega']]);
 
-			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', op: 's', keys: ['foo', 'alpha'] }]]);
+			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['foo', 'alpha'] }]]);
 			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(1);
 		});
 
-		it('should call onSet for each item', async () => {
-			const fakeOnSet = jest.fn(() => Promise.resolve());
+		it('should call onChanged once with all items', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
 			const cache = makeCache<string>({
 				name: 'fake',
-				onSet: fakeOnSet,
+				onChanged: fakeOnChanged,
 			});
 
 			await cache.setMany([['foo', 'bar'], ['alpha', 'omega']]);
 
-			expect(fakeOnSet).toHaveBeenCalledWith('foo', cache);
-			expect(fakeOnSet).toHaveBeenCalledWith('alpha', cache);
+			expect(fakeOnChanged).toHaveBeenCalledWith(['foo', 'alpha'], cache);
+			expect(fakeOnChanged).toHaveBeenCalledTimes(1);
 		});
 
 		it('should emit events only for changed items', async () => {
-			const fakeOnSet = jest.fn(() => Promise.resolve());
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
 			const cache = makeCache<string>({
 				name: 'fake',
-				onSet: fakeOnSet,
+				onChanged: fakeOnChanged,
 			});
 
 			await cache.set('foo', 'bar');
-			fakeOnSet.mockClear();
+			fakeOnChanged.mockClear();
 			fakeInternalEventService._reset();
 
 			await cache.setMany([['foo', 'bar'], ['alpha', 'omega']]);
 
-			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', op: 's', keys: ['alpha'] }]]);
+			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['alpha'] }]]);
+			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(1);
+			expect(fakeOnChanged).toHaveBeenCalledWith(['alpha'], cache);
+			expect(fakeOnChanged).toHaveBeenCalledTimes(1);
+		});
+	});
+
+	describe('getMany', () => {
+		it('should return empty for empty input', () => {
+			const cache = makeCache();
+			const result = cache.getMany([]);
+			expect(result).toEqual([]);
+		});
+
+		it('should return the value for all keys', () => {
+			const cache = makeCache();
+			cache.add('foo', 'bar');
+			cache.add('alpha', 'omega');
+
+			const result = cache.getMany(['foo', 'alpha']);
+
+			expect(result).toEqual([['foo', 'bar'], ['alpha', 'omega']]);
+		});
+
+		it('should return undefined for missing keys', () => {
+			const cache = makeCache();
+			cache.add('foo', 'bar');
+
+			const result = cache.getMany(['foo', 'alpha']);
+
+			expect(result).toEqual([['foo', 'bar'], ['alpha', undefined]]);
+		});
+	});
+
+	describe('fetchMany', () => {
+		it('should do nothing for empty input', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
+			const cache = makeCache({
+				onChanged: fakeOnChanged,
+			});
+
+			await cache.fetchMany([]);
+
+			expect(fakeOnChanged).not.toHaveBeenCalled();
+			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(0);
+		});
+
+		it('should return existing items', async () => {
+			const cache = makeCache();
+			cache.add('foo', 'bar');
+			cache.add('alpha', 'omega');
+
+			const result = await cache.fetchMany(['foo', 'alpha']);
+
+			expect(result).toEqual([['foo', 'bar'], ['alpha', 'omega']]);
+		});
+
+		it('should return existing items without events', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
+			const cache = makeCache({
+				onChanged: fakeOnChanged,
+			});
+			cache.add('foo', 'bar');
+			cache.add('alpha', 'omega');
+
+			await cache.fetchMany(['foo', 'alpha']);
+
+			expect(fakeOnChanged).not.toHaveBeenCalled();
+			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(0);
+		});
+
+		it('should call bulkFetcher for missing items', async () => {
+			const cache = makeCache({
+				bulkFetcher: keys => keys.map(k => [k, `${k}#many`]),
+				fetcher: key => `${key}#single`,
+			});
+
+			const results = await cache.fetchMany(['foo', 'alpha']);
+
+			expect(results).toEqual([['foo', 'foo#many'], ['alpha', 'alpha#many']]);
+		});
+
+		it('should call bulkFetcher only once', async () => {
+			const mockBulkFetcher = jest.fn((keys: string[]) => keys.map(k => [k, `${k}#value`] as [string, string]));
+			const cache = makeCache({
+				bulkFetcher: mockBulkFetcher,
+			});
+
+			await cache.fetchMany(['foo', 'bar']);
+
+			expect(mockBulkFetcher).toHaveBeenCalledTimes(1);
+		});
+
+		it('should call fetcher when fetchMany is undefined', async () => {
+			const cache = makeCache({
+				fetcher: key => `${key}#single`,
+			});
+
+			const results = await cache.fetchMany(['foo', 'alpha']);
+
+			expect(results).toEqual([['foo', 'foo#single'], ['alpha', 'alpha#single']]);
+		});
+
+		it('should call onChanged', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
+			const cache = makeCache({
+				onChanged: fakeOnChanged,
+				fetcher: k => k,
+			});
+
+			await cache.fetchMany(['foo', 'alpha']);
+
+			expect(fakeOnChanged).toHaveBeenCalledWith(['foo', 'alpha'], cache);
+			expect(fakeOnChanged).toHaveBeenCalledTimes(1);
+		});
+
+		it('should call onChanged only for changed', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
+			const cache = makeCache({
+				onChanged: fakeOnChanged,
+				fetcher: k => k,
+			});
+			cache.add('foo', 'bar');
+
+			await cache.fetchMany(['foo', 'alpha']);
+
+			expect(fakeOnChanged).toHaveBeenCalledWith(['alpha'], cache);
+			expect(fakeOnChanged).toHaveBeenCalledTimes(1);
+		});
+
+		it('should not emit event', async () => {
+			const cache = makeCache({
+				fetcher: k => k,
+			});
+
+			await cache.fetchMany(['foo', 'alpha']);
+
+			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(0);
+		});
+	});
+
+	describe('refreshMany', () => {
+		it('should do nothing for empty input', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
+			const cache = makeCache({
+				onChanged: fakeOnChanged,
+			});
+
+			const result = await cache.refreshMany([]);
+
+			expect(result).toEqual([]);
+			expect(fakeOnChanged).not.toHaveBeenCalled();
+			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(0);
+		});
+
+		it('should call bulkFetcher for all keys', async () => {
+			const mockBulkFetcher = jest.fn((keys: string[]) => keys.map(k => [k, `${k}#value`] as [string, string]));
+			const cache = makeCache({
+				bulkFetcher: mockBulkFetcher,
+			});
+
+			const result = await cache.refreshMany(['foo', 'alpha']);
+
+			expect(result).toEqual([['foo', 'foo#value'], ['alpha', 'alpha#value']]);
+			expect(mockBulkFetcher).toHaveBeenCalledWith(['foo', 'alpha'], cache);
+			expect(mockBulkFetcher).toHaveBeenCalledTimes(1);
+		});
+
+		it('should replace any existing keys', async () => {
+			const mockBulkFetcher = jest.fn((keys: string[]) => keys.map(k => [k, `${k}#value`] as [string, string]));
+			const cache = makeCache({
+				bulkFetcher: mockBulkFetcher,
+			});
+			cache.add('foo', 'bar');
+
+			const result = await cache.refreshMany(['foo', 'alpha']);
+
+			expect(result).toEqual([['foo', 'foo#value'], ['alpha', 'alpha#value']]);
+			expect(mockBulkFetcher).toHaveBeenCalledWith(['foo', 'alpha'], cache);
+			expect(mockBulkFetcher).toHaveBeenCalledTimes(1);
+		});
+
+		it('should call onChanged for all keys', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
+			const cache = makeCache({
+				bulkFetcher: keys => keys.map(k => [k, `${k}#value`]),
+				onChanged: fakeOnChanged,
+			});
+			cache.add('foo', 'bar');
+
+			await cache.refreshMany(['foo', 'alpha']);
+
+			expect(fakeOnChanged).toHaveBeenCalledWith(['foo', 'alpha'], cache);
+			expect(fakeOnChanged).toHaveBeenCalledTimes(1);
+		});
+
+		it('should emit event for all keys', async () => {
+			const cache = makeCache({
+				name: 'fake',
+				bulkFetcher: keys => keys.map(k => [k, `${k}#value`]),
+			});
+			cache.add('foo', 'bar');
+
+			await cache.refreshMany(['foo', 'alpha']);
+
+			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['foo', 'alpha'] }]]);
 			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(1);
-			expect(fakeOnSet).toHaveBeenCalledWith('alpha', cache);
-			expect(fakeOnSet).toHaveBeenCalledTimes(1);
 		});
 	});
 
@@ -325,33 +528,33 @@ describe(QuantumKVCache, () => {
 
 			await cache.deleteMany(['foo', 'alpha']);
 
-			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', op: 'd', keys: ['foo', 'alpha'] }]]);
+			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['foo', 'alpha'] }]]);
 			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(1);
 		});
 
-		it('should call onDelete for each key', async () => {
-			const fakeOnDelete = jest.fn(() => Promise.resolve());
+		it('should call onChanged once with all items', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
 			const cache = makeCache<string>({
 				name: 'fake',
-				onDelete: fakeOnDelete,
+				onChanged: fakeOnChanged,
 			});
 
 			await cache.deleteMany(['foo', 'alpha']);
 
-			expect(fakeOnDelete).toHaveBeenCalledWith('foo', cache);
-			expect(fakeOnDelete).toHaveBeenCalledWith('alpha', cache);
+			expect(fakeOnChanged).toHaveBeenCalledWith(['foo', 'alpha'], cache);
+			expect(fakeOnChanged).toHaveBeenCalledTimes(1);
 		});
 
 		it('should do nothing if no keys are provided', async () => {
-			const fakeOnDelete = jest.fn(() => Promise.resolve());
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
 			const cache = makeCache<string>({
 				name: 'fake',
-				onDelete: fakeOnDelete,
+				onChanged: fakeOnChanged,
 			});
 
 			await cache.deleteMany([]);
 
-			expect(fakeOnDelete).not.toHaveBeenCalled();
+			expect(fakeOnChanged).not.toHaveBeenCalled();
 			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(0);
 		});
 	});
@@ -392,17 +595,17 @@ describe(QuantumKVCache, () => {
 			expect(result).toBe('value#foo');
 		});
 
-		it('should call onSet', async () => {
-			const fakeOnSet = jest.fn(() => Promise.resolve());
+		it('should call onChanged', async () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
 			const cache = makeCache<string>({
 				name: 'fake',
 				fetcher: key => `value#${key}`,
-				onSet: fakeOnSet,
+				onChanged: fakeOnChanged,
 			});
 
 			await cache.refresh('foo');
 
-			expect(fakeOnSet).toHaveBeenCalledWith('foo', cache);
+			expect(fakeOnChanged).toHaveBeenCalledWith(['foo'], cache);
 		});
 
 		it('should emit event', async () => {
@@ -413,7 +616,7 @@ describe(QuantumKVCache, () => {
 
 			await cache.refresh('foo');
 
-			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', op: 's', keys: ['foo'] }]]);
+			expect(fakeInternalEventService._calls).toContainEqual(['emit', ['quantumCacheUpdated', { name: 'fake', keys: ['foo'] }]]);
 		});
 	});
 
@@ -434,15 +637,15 @@ describe(QuantumKVCache, () => {
 			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(0);
 		});
 
-		it('should not call onSet', () => {
-			const fakeOnSet = jest.fn(() => Promise.resolve());
+		it('should not call onChanged', () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
 			const cache = makeCache({
-				onSet: fakeOnSet,
+				onChanged: fakeOnChanged,
 			});
 
 			cache.add('foo', 'bar');
 
-			expect(fakeOnSet).not.toHaveBeenCalled();
+			expect(fakeOnChanged).not.toHaveBeenCalled();
 		});
 	});
 
@@ -466,15 +669,15 @@ describe(QuantumKVCache, () => {
 			expect(fakeInternalEventService._calls.filter(c => c[0] === 'emit')).toHaveLength(0);
 		});
 
-		it('should not call onSet', () => {
-			const fakeOnSet = jest.fn(() => Promise.resolve());
+		it('should not call onChanged', () => {
+			const fakeOnChanged = jest.fn(() => Promise.resolve());
 			const cache = makeCache({
-				onSet: fakeOnSet,
+				onChanged: fakeOnChanged,
 			});
 
 			cache.addMany([['foo', 'bar'], ['alpha', 'omega']]);
 
-			expect(fakeOnSet).not.toHaveBeenCalled();
+			expect(fakeOnChanged).not.toHaveBeenCalled();
 		});
 	});