React Patterns
React and Next.js performance optimization — curated rules across priority categories drawn from framework docs and production practice.
Complements mk:typescript (type safety) and mk:vue (Vue patterns). This skill covers React-specific performance patterns.
When to Use
- Writing or reviewing React/Next.js components
- Optimizing bundle size or render performance
- Fixing re-render issues
- Server vs client component decisions
- Data fetching patterns
Rule Categories (by priority)
Load the relevant reference when working in that area:
| Priority | Category | Reference | Key rules | | -------- | ---------------------- | ------------------------------------- | ----------------------------------------------------- | | CRITICAL | Eliminating waterfalls | references/async-patterns.md | Defer await, parallel promises, Suspense boundaries | | CRITICAL | Bundle size | references/bundle-optimization.md | No barrel imports, dynamic imports, defer third-party | | HIGH | Server performance | references/server-patterns.md | React.cache(), LRU cache, parallel fetching, after() | | MEDIUM | Re-render optimization | references/rerender-optimization.md | Derived state, functional setState, memo, transitions | | MEDIUM | Rendering perf | references/rendering-patterns.md | content-visibility, hoist JSX, conditional render |
Process
- Identify the performance concern (waterfall? bundle? re-render? server?)
- Load the matching reference file
- Apply rules — each rule has: problem, solution, code example
- Verify improvement (Lighthouse, bundle analyzer, React DevTools)
Gotchas
- Premature optimization: optimizing re-renders before measuring → measure first with React DevTools Profiler
- Over-memoizing: wrapping everything in useMemo/React.memo → memo only when profiler shows expensive re-renders
- Barrel file trap: importing from index.ts pulls entire module → always import directly from source file
Workflow Integration
Auto-activates during Phase 3 (Build) when React/Next.js project detected. Loaded by developer agent alongside mk:typescript.