How to Optimise a Next.js Web App

Next.js is a powerful framework that offers server-side rendering, static site generation, and incremental static regeneration out of the box. However, as your application grows, maintaining optimal performance requires deliberate optimization strategies. Here is a comprehensive guide to auditing and boosting your Next.js application's speed.

1. Image Optimization with next/image

Images are often the largest assets on a page. The next/image component optimizes images on demand, converts them to modern formats (like WebP or AVIF), and prevents layout shifts (CLS).

import Image from 'next/image';

export default function Profile() {
  return (
    <Image
      src="/avatar.png"
      alt="User Avatar"
      width={120}
      height={120}
      priority // Use priority for LCP images!
    />
  );
}

2. Code Splitting and Dynamic Imports

Next.js automatically splits your JavaScript bundles, but you can optimize this further by using next/dynamic to lazy-load heavy components only when they are needed.

import dynamic from 'next/dynamic';

const DynamicChart = dynamic(() => import('@/components/heavy-chart'), {
  loading: () => <p>Loading chart...</p>,
  ssr: false, // Set to false if it uses browser-only APIs
});

3. Font Optimization

Use next/font to automatically host and load Google Fonts locally, eliminating layout shifts and network requests to external servers.

import { Inter } from 'next/font/google';

const inter = Inter({ subsets: ['latin'] });

By combining these techniques, you can ensure a flawless, blazing-fast experience for your users.