Miguel Palhas
4.4 KiB
4.4 KiB
description
| description |
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| React and Next.js performance optimization guidelines from Vercel Engineering. 45 rules across 8 categories, prioritized by impact. |
Vercel React Best Practices
Comprehensive performance optimization guide for React and Next.js applications. 45 rules across 8 categories, prioritized by impact.
When to Apply
- Writing new React components or Next.js pages
- Implementing data fetching (client or server-side)
- Reviewing code for performance issues
- Refactoring existing React/Next.js code
- Optimizing bundle size or load times
Rule Categories by Priority
| Priority | Category | Impact | Prefix |
|---|---|---|---|
| 1 | Eliminating Waterfalls | CRITICAL | async- |
| 2 | Bundle Size Optimization | CRITICAL | bundle- |
| 3 | Server-Side Performance | HIGH | server- |
| 4 | Client-Side Data Fetching | MEDIUM-HIGH | client- |
| 5 | Re-render Optimization | MEDIUM | rerender- |
| 6 | Rendering Performance | MEDIUM | rendering- |
| 7 | JavaScript Performance | LOW-MEDIUM | js- |
| 8 | Advanced Patterns | LOW | advanced- |
1. Eliminating Waterfalls (CRITICAL)
- async-defer-await - Move await into branches where actually used
- async-parallel - Use Promise.all() for independent operations
- async-dependencies - Use better-all for partial dependencies
- async-api-routes - Start promises early, await late in API routes
- async-suspense-boundaries - Use Suspense to stream content
2. Bundle Size Optimization (CRITICAL)
- bundle-barrel-imports - Import directly, avoid barrel files
- bundle-dynamic-imports - Use next/dynamic for heavy components
- bundle-defer-third-party - Load analytics/logging after hydration
- bundle-conditional - Load modules only when feature is activated
- bundle-preload - Preload on hover/focus for perceived speed
3. Server-Side Performance (HIGH)
- server-cache-react - Use React.cache() for per-request deduplication
- server-cache-lru - Use LRU cache for cross-request caching
- server-serialization - Minimize data passed to client components
- server-parallel-fetching - Restructure components to parallelize fetches
- server-after-nonblocking - Use after() for non-blocking operations
4. Client-Side Data Fetching (MEDIUM-HIGH)
- client-swr-dedup - Use SWR for automatic request deduplication
- client-event-listeners - Deduplicate global event listeners
5. Re-render Optimization (MEDIUM)
- rerender-defer-reads - Don't subscribe to state only used in callbacks
- rerender-memo - Extract expensive work into memoized components
- rerender-dependencies - Use primitive dependencies in effects
- rerender-derived-state - Subscribe to derived booleans, not raw values
- rerender-functional-setstate - Use functional setState for stable callbacks
- rerender-lazy-state-init - Pass function to useState for expensive values
- rerender-transitions - Use startTransition for non-urgent updates
6. Rendering Performance (MEDIUM)
- rendering-animate-svg-wrapper - Animate div wrapper, not SVG element
- rendering-content-visibility - Use content-visibility for long lists
- rendering-hoist-jsx - Extract static JSX outside components
- rendering-svg-precision - Reduce SVG coordinate precision
- rendering-hydration-no-flicker - Use inline script for client-only data
- rendering-activity - Use Activity component for show/hide
- rendering-conditional-render - Use ternary, not && for conditionals
7. JavaScript Performance (LOW-MEDIUM)
- js-batch-dom-css - Group CSS changes via classes or cssText
- js-index-maps - Build Map for repeated lookups
- js-cache-property-access - Cache object properties in loops
- js-cache-function-results - Cache function results in module-level Map
- js-cache-storage - Cache localStorage/sessionStorage reads
- js-combine-iterations - Combine multiple filter/map into one loop
- js-length-check-first - Check array length before expensive comparison
- js-early-exit - Return early from functions
- js-hoist-regexp - Hoist RegExp creation outside loops
- js-min-max-loop - Use loop for min/max instead of sort
- js-set-map-lookups - Use Set/Map for O(1) lookups
- js-tosorted-immutable - Use toSorted() for immutability
8. Advanced Patterns (LOW)
- advanced-event-handler-refs - Store event handlers in refs
- advanced-use-latest - useLatest for stable callback refs
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