Performance in React 19

Optimizing performance ensures fast load times and smooth user experiences. React 19 provides several tools and patterns for building high-performance apps.

Code Splitting & Lazy Loading

• Use dynamic imports to split code and load components on demand:

  const UserProfile = React.lazy(() => import('./UserProfile'));

• Lazy load routes with React Router:

  import { lazy } from 'react';
  const ProfileView = lazy(() => import('./ProfileView'));

Asset Optimization

• Compress images and use modern formats (WebP, AVIF).
• Minify CSS and JavaScript during build.
• Use SVGs for icons and simple graphics.

Caching

• Set cache headers for static assets.
• Use service workers for offline support (via PWA plugins).

Profiling & Monitoring

• Use React DevTools for component performance profiling.
• Monitor bundle size with Vite or Webpack analysis tools.
• Track runtime performance with browser devtools and Lighthouse.

Best Practices

• Avoid unnecessary re-renders and deep prop drilling.
• Debounce or throttle expensive operations (e.g., API calls, input events).
• Memoize components and hooks with React.memo and useMemo.

References

• React Performance Guide
• Vite Build Analysis
• Google Lighthouse