Review Performance

Review performance

Run a performance-focused review: algorithmic complexity, data structures, memory leaks, bundle size, critical path, cache strategy, images, and Worker cold starts. Your reply must be a plan of suggested changes: concise, actionable, and structured-not only prose.

Invocation

Text after the slash command is additional scope/focus - narrow the review accordingly. If none given, use the default scope described below.

Best practices alignment

• Algorithms and data structures - Prefer O(n) or better for hot paths; avoid redundant loops, repeated sorts, or nested iterations over large collections; use appropriate structures (Map/Set for lookups, avoid repeated array scans).
• Memory - No closure or WeakRef leaks in long-lived Workers; no unbounded caches or growing global state; React effects and subscriptions cleaned up on unmount.
• Frontend - Critical path minimal; lazy load below-the-fold; fetchpriority for LCP; explicit dimensions to avoid CLS; code-splitting and tree-shaking; prefetch where beneficial.
• Caching - Cache TTLs and keys match content type (HTML vs assets vs API); no over-caching of dynamic content or under-caching of static; Cloudflare asset and API cache headers correct.
• Worker and API - Bundle size within limits (e.g. < 1 MB compressed for Workers); no blocking I/O on critical path; cold start impact minimized (small deps, no heavy init).

Align with root AGENTS.md and app AGENTS.md for build and deployment model.

Deep technical review

Conduct a performance-only review. Inspect the following and call out violations or improvements.

Algorithmic complexity and data structures

• Artifacts: apps/front-app/src/utils/ and other hot paths, apps/worker-api/src/ (routes, handlers).
• Checks: No O(n²) or worse in hot paths. Filter/map/reduce chains: single pass where possible; avoid repeated .find() in loops (use Map). Sort once and reuse; avoid heavy work in render. Pagination or limits on large lists. worker-api: no N+1 patterns; batch or single queries where appropriate.

Memory leaks and long-lived state

• Artifacts: apps/worker-api/src/index.ts, apps/front-app/src/ (effects, subscriptions, global listeners).
• Checks: worker-api: no unbounded in-memory caches (or use TTL/eviction). No closures capturing request-specific data in global scope. Client: no timers or listeners without cleanup on unmount. No accumulating state in module scope across requests in Workers.

Frontend critical path and bundle size

• Artifacts: apps/front-app/vite.config.ts, apps/front-app/src/main.tsx, apps/front-app/src/routes/, apps/front-app/src/pages/, components under apps/front-app/src/.
• Checks: Vite: TanStack Router autoCodeSplitting per route; no single huge bundle without reason. Tree-shaking: avoid barrel imports that pull in unused code; check for side-effectful imports. Prefetch or preload for high-probability next navigation when added. LCP: hero or main image has fetchpriority="high" and appropriate size where applicable; no render-blocking scripts on critical path.

Images and layout stability

• Artifacts: Images in apps/front-app/src/ and apps/front-app/public/.
• Checks: Modern formats where used; quality and dimensions appropriate (no oversized source). Lazy loading: below-the-fold images use loading="lazy"; above-the-fold do not. Explicit width/height or aspect-ratio to prevent CLS. Responsive srcset/sizes where relevant.

Edge cache and static assets

• Artifacts: apps/front-app/wrangler.jsonc, Cloudflare dashboard or headers for static asset caching (as configured).
• Checks: Cache TTLs appropriate for hashed static assets vs HTML shell. API responses: Cache-Control and dynamic vs static content. No redundant revalidation on the critical path.

worker-api: cold start and request path

• Artifacts: apps/worker-api/src/index.ts, apps/worker-api/package.json, apps/worker-api/wrangler.jsonc.
• Checks: Bundle size: keep under Cloudflare limits (e.g. 1 MB compressed); avoid large transitive deps if possible. No heavy sync work at top-level (module init); defer to request handler. External calls: timeouts set; no blocking on critical path when avoidable. Health route: minimal work for fast cold start signal.

Network and payloads

• Artifacts: API routes, any fetch from front-app to worker-api.
• Checks: No duplicate requests for same resource (dedupe or cache). Payload size reasonable. Compression: gzip/brotli often at edge. Prefetch only for high-probability next navigation.

Anti-patterns to flag

• O(n²) or worse in hot paths or request handlers.
• Unbounded in-memory cache or growing global state in Workers.
• LCP image without dimensions or without fetchpriority; lazy loading on LCP image.
• Single large JS bundle; no code-splitting for routes.
• Cache-Control missing or wrong for content type; caching dynamic API responses too aggressively.
• Blocking I/O or heavy init on Worker request path.
• Worker bundle bloated by unnecessary dependencies.

Steps

1. Gather scope - Full performance or specific area (algorithms, frontend, cache, images, worker-api). Default to full.
2. Read conventions - AGENTS.md for build and Worker behavior.
3. Inspect hot paths - front-app utils and worker-api handlers; reason about complexity and data structures.
4. Inspect Worker and React - Long-lived state, caches, listeners; identify leak risks.
5. Inspect frontend build and images - vite.config.ts, component usage; bundle and CLS.
6. Inspect cache strategy - wrangler, headers, TTLs where applicable.
7. Inspect worker-api - Bundle size, init cost, external calls and timeouts.
8. Compose plan - Critical / Improvements / Optional; each item: what, where, why. One-line "no issues" per sub-area if none.

Checklist

• Scope clear
• AGENTS.md consulted for build and Worker model
• Algorithmic complexity and data structures reviewed
• Memory and long-lived state (Worker, React) reviewed
• Frontend critical path, bundle, and code-splitting reviewed
• Images and CLS reviewed
• Edge cache / asset strategy reviewed
• worker-api cold start and request path reviewed
• Plan structured as Critical / Improvements / Optional with what/where/why

Context usage

• Use @file for vite.config.ts, worker-api index, image usage in components.
• Use @code for specific loops, cache logic, or image usage when suggesting changes.
• Use @docs for Vite/Cloudflare Worker limits and best practices.

If context is insufficient, suggest which files or @ references to add.

Review checklist

• Correctness: Complexity claims and cache semantics are accurate; no incorrect optimizations.
• Conventions: Aligns with AGENTS.md (Vite SPA + worker-api responsibilities).
• Quality: Measurable or reasoned impact (e.g. "reduces complexity from O(n²) to O(n)").
• Actionability: Every suggestion is implementable (e.g. "use Map for lookup", "add width/height to image").
• Trade-offs: Note any (e.g. cache TTL vs freshness, bundle size vs features).
• Scope: Performance only; defer SEO or security to their reviews.

Output format

Respond with a plan only (no implementation unless the user asks):

1. Critical – Must-fix (severe complexity, memory leak, broken cache, LCP/CLS regression).
2. Improvements – Worthwhile (better data structure, cache TTL, fetchpriority, code-split).
3. Optional – Nice-to-haves (minor refactor, prefetch tuning). Prefix with Nit: for non-blocking polish.

For each item: what to change, where (file/area), and why. If a sub-area has no findings, state it in one line.