[HIGH] Replace O(n) .find() linear scans with Map lookups in database.ts #36

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opened 2026-06-09 00:03:13 +00:00 by Mark · 0 comments

Mark commented

2026-06-09 00:03:13 +00:00

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Locations: backend/src/database.ts across getUserById, getSubscriptionById, etc.

Problem: All lookups use .find() on arrays, which is O(n). Combined with the full-file reads on every call, this compounds the performance problem.

Impact: Linear scan becomes a bottleneck as user/subscription count grows.

Fix: Build Map<string, User> keyed by id and by email at startup; update on mutations. O(n) → O(1).

Effort: Included in CRITICAL database cache fix

**Locations:** `backend/src/database.ts` across `getUserById`, `getSubscriptionById`, etc. **Problem:** All lookups use `.find()` on arrays, which is O(n). Combined with the full-file reads on every call, this compounds the performance problem. **Impact:** Linear scan becomes a bottleneck as user/subscription count grows. **Fix:** Build `Map<string, User>` keyed by `id` and by `email` at startup; update on mutations. O(n) → O(1). **Effort:** Included in CRITICAL database cache fix