Next.js Performance Optimization Guide 2025
Master Next.js performance with this comprehensive guide. Learn best practices for static generation, image optimization, and achieving perfect Lighthouse scores.
Next.js Strengths
- Static Site Generation (SSG) for instant TTFB
- Automatic image optimization with next/image
- Built-in font optimization with next/font
- Automatic code splitting and lazy loading
- Edge runtime support for dynamic content
- Server Components reduce client-side JavaScript
Common Challenges
- Large JavaScript bundles without proper code splitting
- Client-side hydration can cause INP issues
- Improper use of client components increases bundle size
- Dynamic imports need careful implementation
- Third-party scripts can still impact performance
Optimization Checklist
Use Static Site Generation (SSG)
Pre-render pages at build time with generateStaticParams for instant loading and zero TTFB.
Leverage Server Components
Default to Server Components and only use "use client" when necessary to minimize client JavaScript.
Use next/image
Always use the Image component for automatic WebP conversion, lazy loading, and responsive sizing.
Implement next/font
Use next/font for automatic font optimization with zero layout shift.
Enable ISR
Use Incremental Static Regeneration for pages that need periodic updates without full rebuilds.
Analyze bundle size
Use next build --analyze to identify large dependencies and code split appropriately.
Use dynamic imports
Dynamically import heavy components that aren't needed for initial render.
Implement route prefetching
Next.js prefetches links automatically, but verify it's working for critical paths.
Frequently Asked Questions
Why is my Next.js app slow despite SSG?+
Common issues include large client-side bundles, hydration overhead, unoptimized images, and third-party scripts. Use Server Components, analyze your bundle, and ensure you're using next/image.
Should I use SSG, SSR, or ISR?+
Use SSG for content that doesn't change often (best performance). Use ISR for content that updates periodically. Use SSR only when you need request-time data. SSG should be your default.
How do I reduce JavaScript bundle size in Next.js?+
Use Server Components (they don't add to client bundle), dynamic imports for heavy components, tree-shake unused code, and analyze with next build --analyze to find large dependencies.
Test Your Next.js Site
See how your Next.js site performs with a free Core Web Vitals test.