Performance is a feature

Users won't complain about performance until it's bad. By then it's expensive to fix.

The easy wins

1. Images — use next/image, specify dimensions, use WebP
2. Fonts — self-host or use next/font, never block render
3. Client JS — every "use client" is a bundle cost. Justify it.
4. Database queries — add indexes before launch, not after

Measure first

Don't optimize blind. Use Lighthouse, use the Network tab, use EXPLAIN ANALYZE on slow queries.

The 80/20 of web performance

• Serve from a CDN
• Lazy load images below the fold
• Don't block the main thread
• Cache aggressively, invalidate precisely

Most sites don't need exotic optimization. They need these four things done well.