Check Your Next.js App Speed
Run a Lighthouse audit on your Next.js application and export the full JSON report. Feed it to Cursor, Claude, or ChatGPT to get exact code changes targeting your specific performance issues.
Loading…
Loading...Common performance issues on Next.js sites
These are the issues most frequently found in Next.js Lighthouse audits. Your report will tell you exactly which ones apply to your site.
Large JavaScript bundles
Client-side JavaScript is the most common performance issue in Next.js apps. The report's "Reduce unused JavaScript" audit identifies specific bundles and their sizes.
Missing image optimization
Using `<img>` instead of Next.js's `<Image>` component misses automatic WebP conversion, responsive sizing, and lazy loading — all of which impact LCP.
Cumulative Layout Shift from dynamic content
Server components that load async data without skeleton screens, or client components that hydrate differently from server HTML, frequently cause CLS issues.
Render-blocking third-party scripts
Scripts loaded without `next/script` and the `strategy` prop (afterInteractive or lazyOnload) block page rendering and increase TBT.
Pro tip: Next.js has excellent built-in tools for most performance issues: use `<Image>` for images, `next/script` for third-party scripts, and Server Components to reduce client-side JavaScript. The Lighthouse report will tell you exactly where your app is deviating from these patterns.
Want a detailed tutorial? Read our step-by-step performance fix guide →