Tag: Webpagetest

This post summarizes how we analyzed publicly available web transparency data and ad hoc A/B testing to understand the adoption and performance characteristics of native image lazy-loading. What we found is that lazy-loading can be an amazingly effective tool for reducing unneeded image bytes, but overuse can negatively affect performance. Concretely, our analysis shows that more eagerly loading images within the initial viewport—while liberally lazy-loading the rest—can give us the best of both worlds: fewer bytes loaded and improved Core Web Vitals.

Super clever stuff from Andy about how he’s using Cloudflare Workers and WebPageTest to test performance optimizations. I’ve done a little of this, but there’s a bunch here I haven’t played with. Going to have to change that for sure!

I always like seeing how other folks handle performance audits. Here, Jake walks through 10 F1 sites, auditing them primarily with WebpageTest and a smattering of Chrome Dev Tools.