diff --git a/packages/backend/src/core/IdService.ts b/packages/backend/src/core/IdService.ts
index 223a8de678..d30093d1db 100644
--- a/packages/backend/src/core/IdService.ts
+++ b/packages/backend/src/core/IdService.ts
@@ -3,40 +3,84 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { Inject, Injectable } from '@nestjs/common';
-import { ulid } from 'ulid';
+import { Inject, Injectable, OnModuleInit } from '@nestjs/common';
 import { DI } from '@/di-symbols.js';
 import type { Config } from '@/config.js';
-import { genAid, isSafeAidT, parseAid, parseAidFull } from '@/misc/id/aid.js';
-import { genAidx, isSafeAidxT, parseAidx, parseAidxFull } from '@/misc/id/aidx.js';
-import { genMeid, isSafeMeidT, parseMeid, parseMeidFull } from '@/misc/id/meid.js';
-import { genMeidg, isSafeMeidgT, parseMeidg, parseMeidgFull } from '@/misc/id/meidg.js';
-import { genObjectId, isSafeObjectIdT, parseObjectId, parseObjectIdFull } from '@/misc/id/object-id.js';
 import { bindThis } from '@/decorators.js';
-import { parseUlid, parseUlidFull } from '@/misc/id/ulid.js';
 
 @Injectable()
-export class IdService {
+export class IdService implements OnModuleInit {
 	private method: string;
+	private safeTFn: (t: number) => boolean;
+	private genFn: (time: number) => string;
+	private parseFn: (id: string) => { date: Date; };
+	private parseFullFn: (id: string) => { date: number; additional: bigint; };
 
 	constructor(
 		@Inject(DI.config)
 		private config: Config,
 	) {
-		this.method = config.id.toLowerCase();
+		this.method = this.config.id.toLowerCase();
+	}
+
+	async onModuleInit() {
+		switch (this.method) {
+			case 'aid': {
+				const aidModule = await import('@/misc/id/aid.js');
+				this.safeTFn = aidModule.isSafeAidT;
+				this.genFn = aidModule.genAid;
+				this.parseFn = aidModule.parseAid;
+				this.parseFullFn = aidModule.parseAidFull;
+				break;
+			}
+			case 'aidx': {
+				const aidxModule = await import('@/misc/id/aidx.js');
+				this.safeTFn = aidxModule.isSafeAidxT;
+				this.genFn = aidxModule.genAidx;
+				this.parseFn = aidxModule.parseAidx;
+				this.parseFullFn = aidxModule.parseAidxFull;
+				break;
+			}
+			case 'meid': {
+				const meidModule = await import('@/misc/id/meid.js');
+				this.safeTFn = meidModule.isSafeMeidT;
+				this.genFn = meidModule.genMeid;
+				this.parseFn = meidModule.parseMeid;
+				this.parseFullFn = meidModule.parseMeidFull;
+				break;
+			}
+			case 'meidg': {
+				const meidgModule = await import('@/misc/id/meidg.js');
+				this.safeTFn = meidgModule.isSafeMeidgT;
+				this.genFn = meidgModule.genMeidg;
+				this.parseFn = meidgModule.parseMeidg;
+				this.parseFullFn = meidgModule.parseMeidgFull;
+				break;
+			}
+			case 'ulid': {
+				const ulidModule = await import('@/misc/id/ulid.js');
+				const { ulid: genUlid } = await import('ulid');
+				this.safeTFn = (t) => t > 0;
+				this.genFn = (time) => genUlid(time);
+				this.parseFn = ulidModule.parseUlid;
+				this.parseFullFn = ulidModule.parseUlidFull;
+				break;
+			}
+			case 'objectid': {
+				const objectIdModule = await import('@/misc/id/object-id.js');
+				this.safeTFn = objectIdModule.isSafeObjectIdT;
+				this.genFn = objectIdModule.genObjectId;
+				this.parseFn = objectIdModule.parseObjectId;
+				this.parseFullFn = objectIdModule.parseObjectIdFull;
+				break;
+			}
+			default: throw new Error('unrecognized id generation method');
+		}
 	}
 
 	@bindThis
 	public isSafeT(t: number): boolean {
-		switch (this.method) {
-			case 'aid': return isSafeAidT(t);
-			case 'aidx': return isSafeAidxT(t);
-			case 'meid': return isSafeMeidT(t);
-			case 'meidg': return isSafeMeidgT(t);
-			case 'ulid': return t > 0;
-			case 'objectid': return isSafeObjectIdT(t);
-			default: throw new Error('unrecognized id generation method');
-		}
+		return this.safeTFn(t);
 	}
 
 	/**
@@ -46,42 +90,17 @@ export class IdService {
 	@bindThis
 	public gen(time?: number): string {
 		const t = (!time || (time > Date.now())) ? Date.now() : time;
-
-		switch (this.method) {
-			case 'aid': return genAid(t);
-			case 'aidx': return genAidx(t);
-			case 'meid': return genMeid(t);
-			case 'meidg': return genMeidg(t);
-			case 'ulid': return ulid(t);
-			case 'objectid': return genObjectId(t);
-			default: throw new Error('unrecognized id generation method');
-		}
+		return this.genFn(t);
 	}
 
 	@bindThis
 	public parse(id: string): { date: Date; } {
-		switch (this.method) {
-			case 'aid': return parseAid(id);
-			case 'aidx': return parseAidx(id);
-			case 'objectid': return parseObjectId(id);
-			case 'meid': return parseMeid(id);
-			case 'meidg': return parseMeidg(id);
-			case 'ulid': return parseUlid(id);
-			default: throw new Error('unrecognized id generation method');
-		}
+		return this.parseFn(id);
 	}
 
 	// Note: additional is at most 64 bits
 	@bindThis
 	public parseFull(id: string): { date: number; additional: bigint; } {
-		switch (this.method) {
-			case 'aid': return parseAidFull(id);
-			case 'aidx': return parseAidxFull(id);
-			case 'objectid': return parseObjectIdFull(id);
-			case 'meid': return parseMeidFull(id);
-			case 'meidg': return parseMeidgFull(id);
-			case 'ulid': return parseUlidFull(id);
-			default: throw new Error('unrecognized id generation method');
-		}
+		return this.parseFullFn(id);
 	}
 }