Next.js 15 App Router: Best Practices for Exceptional Performance

The most important App Router rule: every component is a Server Component by default unless you add "use client" — meaning more logic runs on the server and less JavaScript ships to the browser.

Use generateMetadata Instead of Manual Head Tags

The async generateMetadata function lets you build dynamic title, description, and Open Graph data based on the page's actual data (like locale or slug) — cleaner and more powerful for SEO than manually placed head tags.

Caching and Revalidation

export const revalidate sets how often a page rebuilds in the background (ISR), an ideal middle ground between a fully static page and a fully dynamic per-request page — very useful for periodically changing content like a blog.