perf-checklisted

# Performance Check Analyze and report on project performance metrics. ## Arguments - `/perf-check` — full analysis - `/perf-check --bundle` — bundle size only - `/perf-check --lighthouse <url>` — Lighthouse audit - `/perf-check --deps` — dependency weight analysis - `/perf-check --code` — code-level pattern check ## Workflow ### Phase 1: Detect Scope - **Frontend**: bundle size, lighthouse, dependency weight - **Backend**: startup time, memory, dependency weight - **Fullstack**: both ### Phase 2: Bundle Analysis - Build and measure output: `du -sh dist/ build/ .next/` - Check largest dependencies: `npx -y cost-of-modules` - Identify tree-shaking opportunities ### Phase 3: Lighthouse (if URL available) ```bash npx -y lighthouse <url> --output json --chrome-flags="--headless --no-sandbox" ``` ### Phase 4: Dependency Analysis Flag heavy dependencies: - `moment` → `dayjs` or `date-fns` - `lodash` (full) → `lodash-es` or individual imports - `aws-sdk` v2 → `@aws-sdk/client-*` v3 ### Phase 5: Code Anti-patterns - N+1 queries (loop with await) - `JSON.parse(JSON.stringify())` for clone - Missing `useMemo`/`useCallback` on expensive operations - Sync file ops in request handlers - Missing database indexes ### Phase 6: Report ```markdown # Performance Report ## Bundle - Total: 1.2MB (gzipped: 380KB) ## Issues Found 🔴 moment.js adds 230KB — replace with dayjs (2KB) 🟡 Full lodash import — use lodash-es ## Recommendations (by impact) 1. Replace moment → dayjs (saves ~228