| name | vercel-react-best-practices |
| description | React and Next.js performance optimization with 69 prioritized rules across 8 categories. Use when writing React components, implementing data fetching, reviewing code for performance, refactoring React/Next.js code, optimizing bundle size, or when the user says "React performance", "optimize React", "Next.js best practices", "bundle size", or "waterfall." Based on vercel-labs/agent-skills (291K weekly installs). |
Vercel React Best Practices
Performance optimization guide for React and Next.js, maintained by Vercel. 69 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-cheap-condition-before-await — Check cheap sync conditions before awaiting flags or remote valuesasync-defer-await — Move await into branches where actually usedasync-parallel — Use Promise.all() for independent operationsasync-dependencies — Use better-all for partial dependenciesasync-api-routes — Start promises early, await late in API routesasync-suspense-boundaries — Use Suspense to stream content
2. Bundle Size Optimization (CRITICAL)
bundle-barrel-imports — Import directly, avoid barrel filesbundle-dynamic-imports — Use next/dynamic for heavy componentsbundle-defer-third-party — Load analytics/logging after hydrationbundle-conditional — Load modules only when feature is activatedbundle-preload — Preload on hover/focus for perceived speed
3. Server-Side Performance (HIGH)
server-auth-actions — Authenticate server actions like API routesserver-cache-react — Use React.cache() for per-request deduplicationserver-cache-lru — Use LRU cache for cross-request cachingserver-dedup-props — Avoid duplicate serialization in RSC propsserver-hoist-static-io — Hoist static I/O (fonts, logos) to module levelserver-no-shared-module-state — Avoid module-level mutable request state in RSC/SSRserver-serialization — Minimize data passed to client componentsserver-parallel-fetching — Restructure components to parallelize fetchesserver-parallel-nested-fetching — Chain nested fetches per item in Promise.allserver-after-nonblocking — Use after() for non-blocking operations
4. Client-Side Data Fetching (MEDIUM-HIGH)
client-swr-dedup — Use SWR for automatic request deduplicationclient-event-listeners — Deduplicate global event listenersclient-passive-event-listeners — Use passive listeners for scrollclient-localstorage-schema — Version and minimize localStorage data
5. Re-render Optimization (MEDIUM)
rerender-defer-reads — Don't subscribe to state only used in callbacksrerender-memo — Extract expensive work into memoized componentsrerender-memo-with-default-value — Hoist default non-primitive propsrerender-dependencies — Use primitive dependencies in effectsrerender-derived-state — Subscribe to derived booleans, not raw valuesrerender-derived-state-no-effect — Derive state during render, not effectsrerender-functional-setstate — Use functional setState for stable callbacksrerender-lazy-state-init — Pass function to useState for expensive valuesrerender-simple-expression-in-memo — Avoid memo for simple primitivesrerender-split-combined-hooks — Split hooks with independent dependenciesrerender-move-effect-to-event — Put interaction logic in event handlersrerender-transitions — Use startTransition for non-urgent updatesrerender-use-deferred-value — Defer expensive renders to keep input responsivererender-use-ref-transient-values — Use refs for transient frequent valuesrerender-no-inline-components — Don't define components inside components
6. Rendering Performance (MEDIUM)
rendering-animate-svg-wrapper — Animate div wrapper, not SVG elementrendering-content-visibility — Use content-visibility for long listsrendering-hoist-jsx — Extract static JSX outside componentsrendering-svg-precision — Reduce SVG coordinate precisionrendering-hydration-no-flicker — Use inline script for client-only datarendering-activity — Use Activity component for show/hiderendering-conditional-render — Use ternary, not && for conditionalsrendering-usetransition-loading — Prefer useTransition for loading staterendering-resource-hints — Use React DOM resource hints for preloading
7. JavaScript Performance (LOW-MEDIUM)
js-batch-dom-css — Group CSS changes via classes or cssTextjs-index-maps — Build Map for repeated lookupsjs-cache-property-access — Cache object properties in loopsjs-combine-iterations — Combine filter/map into one loopjs-length-check-first — Check array length before expensive comparisonjs-early-exit — Return early from functionsjs-hoist-regexp — Hoist RegExp creation outside loopsjs-set-map-lookups — Use Set/Map for O(1) lookupsjs-flatmap-filter — Use flatMap to map and filter in one passjs-request-idle-callback — Defer non-critical work to browser idle time
8. Advanced Patterns (LOW)
advanced-effect-event-deps — Don't put useEffectEvent results in effect depsadvanced-event-handler-refs — Store event handlers in refsadvanced-init-once — Initialize app once per app loadadvanced-use-latest — useLatest for stable callback refs
Related Skills
web-design-guidelines — Vercel Web Interface Guidelines compliancefrontend-design — Distinctive frontend aesthetics (Anthropic)seo-geo-optimization — AI search optimization for pages
