Page speed basics

The changes that improve almost every slow site, in the order worth doing them.

1 hour

why this matters

Roughly every 100ms you remove from load time is worth about a percent of conversion rate. These are the highest-return changes.

1
Compress your images
Images are usually most of a page's weight. Convert to WebP or AVIF, resize to the dimensions actually displayed, and add loading="lazy" to everything below the fold.
2
Turn on text compression and caching
Serve HTML, CSS and JS with Brotli or gzip, and give static assets a long cache lifetime with hashed filenames.
```
Cache-Control: public, max-age=31536000, immutable
```
3
Put a CDN in front of everything
Serving assets from a location near the visitor cuts hundreds of milliseconds for anyone not next door to your server.
4
Cut what you don't need
Remove unused CSS and JavaScript, drop unused webfont weights, and delete abandoned marketing tags. Deleting code is the fastest optimisation there is.
5
Measure real visitors, not just the lab
Lab scores vary run to run. Collect field Core Web Vitals from actual visitors so you know what your customers experience.