react-best-practices

Use Promise.all() for independent async operations, defer await into branches where results are actually used, and start promises early in API routes before awaiting them. For partial dependencies, the better-all library maximizes parallelism automatically.

Import directly from source files instead of barrel files like lucide-react or @mui/material entry points, use next/dynamic for heavy components, and defer analytics libraries until after hydration. Next.js 13.5+ also offers optimizePackageImports for automatic transformation.

Yes, the rules cover both server-side and client-side patterns. Server rules address RSC serialization, React.cache() deduplication, and parallel data fetching, while client rules cover SWR, event listeners, and re-render optimization.

React.cache() deduplicates requests within a single request lifecycle, ideal for authentication and database queries. Use an LRU cache like lru-cache when data must persist across sequential requests, such as repeated user actions hitting multiple endpoints.

Barrel files from libraries like lucide-react or @mui/material can re-export thousands of modules, adding 200-800ms import cost on every cold start and slowing builds. Direct imports load only the modules you use, improving dev boot, build times, and HMR.