Lab score

One test, one machine

A tool loads your page once, in a controlled environment, and estimates a score. Useful for diagnosis — but it's a single lab run, not your audience.

Field data — our focus

Thousands of real visits

Google's Chrome UX Report (CrUX) collects performance from actual Chrome users on your site over 28 days. This is the experience we optimize for.

We optimize for the experience on the right: real users, measured over time.