Next.js 14: Best Practices for Ultra-Performant Web Apps

Next.js 14 represents a major evolution in React web development. With the App Router, Server Components and Server Actions, Vercel's framework pushes the boundaries of web performance. Here are the best practices to make the most of it.

The App Router: a new way of thinking

The App Router introduces an architecture based on React Server Components (RSC). By default, all components are Server Components — they run on the server and only send HTML to the client. This considerably reduces the JavaScript sent to the browser.

The golden rule: only use 'use client' when you need interactivity (useState, useEffect, event handlers). For everything else, stay on the server.

Server Components and Data Fetching

Fetching directly in components

With Server Components, you can fetch data directly in your components without useEffect or API routes:

Requests are automatically deduplicated by React — even if several components fetch the same URL, the request is only made once.

Streaming with Suspense

Use Suspense to stream the slow parts of your page:

The user sees available content immediately, while slower parts (external data, computations) arrive progressively.

Server Actions: forms without API routes

Server Actions let you handle server-side data mutations directly from your components, without creating API routes:

No need to create an API endpoint for every action — Next.js automatically generates a secure endpoint.

Image optimization

Next.js 14 further improves its Image component. Always use next/image instead of a plain img tag: automatic compression, lazy loading, WebP/AVIF format, and prevention of Cumulative Layout Shift (CLS).

Font optimization

Use next/font to load your fonts without layout shift and without a request to Google Fonts in production:

Fonts are self-hosted and automatically optimized.

Metadata and SEO

Next.js 14 offers a powerful Metadata API for SEO. Use the metadata export for static pages and generateMetadata for dynamic pages.

Partial Prerendering (Experimental)

Partial Prerendering (PPR) is the most promising feature of Next.js 14. It combines static and dynamic rendering within the same page: the static shell is served instantly from the CDN, while the dynamic parts stream in progressively.

Conclusion

Next.js 14 is the most mature and performant React framework on the market. By adopting Server Components, Server Actions and Streaming, you can achieve 90+ Lighthouse scores on complex applications. At Kalix Technologies, we've used Next.js 14 on all our web projects since its release.