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vercel-react-best-practices

vercel-labs/agent-skills

70 React/Next.js performance rules from Vercel Engineering, prioritized by impact for writing, reviewing, and refactoring code.

Source View on skills.sh

What is vercel-react-best-practices?

vercel-react-best-practices installs a structured set of 70 performance optimization rules for React and Next.js, organized into 8 priority tiers from CRITICAL (waterfall elimination, bundle size) to LOW (advanced patterns). Each rule includes a rationale, a bad code example, and a correct code example. The skill is designed to guide coding agents when generating new components, reviewing existing code, or refactoring for performance.

Provides 70 named, prefixed rules covering React and Next.js performance across 8 categories
Prioritizes rules by impact level (CRITICAL → LOW) so agents tackle the highest-value issues first
Covers waterfall elimination using Promise.all, Suspense, and deferred awaits
Addresses bundle size via dynamic imports, direct imports, and deferred third-party loading
Guides server-side patterns including React.cache(), LRU caching, and RSC serialization
Covers client-side re-render optimization, rendering performance, and JavaScript micro-optimizations

How to install vercel-react-best-practices

npx skills add https://github.com/vercel-labs/agent-skills --skill vercel-react-best-practices

Prerequisites

Project must use React (any version supporting hooks) or Next.js
Coding agent must support SKILL.md-based skill installation (e.g., Claude Code, Cursor)
Node.js and npx available to run the install command
Familiarity with React hooks and Next.js App Router is helpful for interpreting rules

Claude Code

Cursor

Windsurf

Cline

How to use vercel-react-best-practices

1.Install the skill: npx skills add https://github.com/vercel-labs/agent-skills --skill vercel-react-best-practices
2.Ask your coding agent to write, review, or refactor a React or Next.js file — the skill triggers automatically on relevant tasks
3.Reference a specific rule by name (e.g., 'apply async-parallel') to target a particular optimization
4.Read individual rule files under rules/<rule-name>.md for detailed explanations and code examples
5.Consult AGENTS.md for the full compiled guide with all 70 rules expanded
6.Use rule prefixes (async-, bundle-, server-, etc.) to scope agent instructions to a category
7.Prioritize CRITICAL-tier rules (async- and bundle-) first when doing a broad performance pass
8.Combine with bundle analysis tools to validate bundle-* rule improvements

Use cases

Good for

Writing new Next.js pages or React components that need to follow performance best practices
Reviewing a pull request for common React performance anti-patterns
Refactoring data fetching code to eliminate request waterfalls
Reducing JavaScript bundle size by replacing barrel imports or adding dynamic imports
Optimizing re-render behavior using memoization, refs, and derived state patterns

Who it's for

Frontend engineers building React or Next.js applications
Coding agents (Claude Code, Cursor) tasked with generating or reviewing React/Next.js code
Teams adopting Vercel infrastructure who want opinionated, Vercel-aligned patterns
Developers preparing for performance audits or Core Web Vitals improvements
Tech leads setting automated code review standards for React projects

vercel-react-best-practices FAQ

Does this skill enforce rules automatically or just provide guidance?

It provides guidelines that coding agents reference when generating or reviewing code. Enforcement depends on how the agent is prompted — it does not add linting or CI checks automatically.

Where are the detailed code examples for each rule?

Each rule has its own file at rules/<rule-name>.md (e.g., rules/async-parallel.md) containing the rationale, a bad example, and a correct example. The full compiled document is in AGENTS.md.

Does this skill work with the Next.js Pages Router or only the App Router?

The skill content covers both, but several rules (RSC props, React.cache, server actions, after()) are specific to the App Router and React Server Components.

How many rules are included and how are they organized?

There are 70 rules across 8 categories, each with a short prefix (async-, bundle-, server-, client-, rerender-, rendering-, js-, advanced-) and an assigned impact level from CRITICAL to LOW.

Can I use this skill outside of Vercel-hosted projects?

Yes. The rules apply to any React or Next.js project. Some server-side rules (e.g., after()) may rely on Vercel-specific APIs, but the majority are framework-level patterns usable anywhere.

Full instructions (SKILL.md)

Source of truth, from vercel-labs/agent-skills.

name: vercel-react-best-practices description: React and Next.js performance optimization guidelines from Vercel Engineering. This skill should be used when writing, reviewing, or refactoring React/Next.js code to ensure optimal performance patterns. Triggers on tasks involving React components, Next.js pages, data fetching, bundle optimization, or performance improvements. license: MIT metadata: author: vercel version: "1.0.0"

Vercel React Best Practices

Comprehensive performance optimization guide for React and Next.js applications, maintained by Vercel. Contains 70 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.

When to Apply

Reference these guidelines when:

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-`

Quick Reference

1. Eliminating Waterfalls (CRITICAL)

async-cheap-condition-before-await - Check cheap sync conditions before awaiting flags or remote values
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-analyzable-paths - Prefer statically analyzable import and file-system paths to avoid broad bundles and traces
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-auth-actions - Authenticate server actions like API routes
server-cache-react - Use React.cache() for per-request deduplication
server-cache-lru - Use LRU cache for cross-request caching
server-dedup-props - Avoid duplicate serialization in RSC props
server-hoist-static-io - Hoist static I/O (fonts, logos) to module level
server-no-shared-module-state - Avoid module-level mutable request state in RSC/SSR
server-serialization - Minimize data passed to client components
server-parallel-fetching - Restructure components to parallelize fetches
server-parallel-nested-fetching - Chain nested fetches per item in Promise.all
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
client-passive-event-listeners - Use passive listeners for scroll
client-localstorage-schema - Version and minimize localStorage data

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-memo-with-default-value - Hoist default non-primitive props
rerender-dependencies - Use primitive dependencies in effects
rerender-derived-state - Subscribe to derived booleans, not raw values
rerender-derived-state-no-effect - Derive state during render, not effects
rerender-functional-setstate - Use functional setState for stable callbacks
rerender-lazy-state-init - Pass function to useState for expensive values
rerender-simple-expression-in-memo - Avoid memo for simple primitives
rerender-split-combined-hooks - Split hooks with independent dependencies
rerender-move-effect-to-event - Put interaction logic in event handlers
rerender-transitions - Use startTransition for non-urgent updates
rerender-use-deferred-value - Defer expensive renders to keep input responsive
rerender-use-ref-transient-values - Use refs for transient frequent values
rerender-no-inline-components - Don't define components inside components

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-hydration-suppress-warning - Suppress expected mismatches
rendering-activity - Use Activity component for show/hide
rendering-conditional-render - Use ternary, not && for conditionals
rendering-usetransition-loading - Prefer useTransition for loading state
rendering-resource-hints - Use React DOM resource hints for preloading
rendering-script-defer-async - Use defer or async on script tags

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
js-flatmap-filter - Use flatMap to map and filter in one pass
js-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 deps
advanced-event-handler-refs - Store event handlers in refs
advanced-init-once - Initialize app once per app load
advanced-use-latest - useLatest for stable callback refs

How to Use

Read individual rule files for detailed explanations and code examples:

rules/async-parallel.md
rules/bundle-barrel-imports.md

Each rule file contains:

Brief explanation of why it matters
Incorrect code example with explanation
Correct code example with explanation
Additional context and references

Full Compiled Document

vercel-labs/agent-skills

Deploy and manage Vercel projects using token-based authentication without interactive login.

60k installs