What are the best ways to implement lazy loading in a Next.js website?
Quick Answer: The best way to implement lazy loading in a Next.js website is to combine Next.js dynamic imports with route-level code splitting, native image optimization, and viewport-triggered loading for below-the-fold components. Use `next/dynamic` for heavy UI modules, `next/image` for automatic responsive image lazy loading, and defer non-critical scripts or widgets until they are actually needed to reduce initial bundle size and improve Core Web Vitals.
Detailed Explanation
In Next.js, effective lazy loading is primarily about minimizing the amount of JavaScript, media, and third-party code delivered on first paint. The most reliable approach is to load non-essential components with `next/dynamic`, which supports client-side code splitting and can optionally disable server-side rendering for browser-only modules. For media, `next/image` provides built-in lazy loading, responsive sizing, and modern format optimization, while viewport-aware patterns such as Intersection Observer can trigger content loading only when sections scroll into view. For enterprise sites, lazy loading should also extend to analytics tags, chat tools, maps, and rich embeds, because third-party scripts frequently create the largest performance bottlenecks. The goal is not to lazy load everything, but to defer only what does not materially affect the first user interaction or above-the-fold content.
Key Technical Drivers
- Use `next/dynamic` to split heavy components into separate chunks, and set `ssr: false` only for browser-dependent modules like charts, editors, or maps.
- Use `next/image` for all non-critical images so Next.js handles lazy loading, responsive `srcset`, format selection, and layout stability without extra custom code.
- Defer third-party assets and below-the-fold UI with Intersection Observer or interaction-based triggers, especially for embeds, chat widgets, review carousels, and analytics scripts.