WebPageTest
Detailed performance testing from real devices and locations, with filmstrips that show what the page looked like while it loaded.
Definition
A performance testing service that loads a page on real hardware over throttled connections and returns waterfalls, Core Web Vitals and a frame-by-frame filmstrip. The filmstrip is what makes it useful in design conversations: it shows the experience rather than the score.
Craft convention. True because the industry converged on it. Breaking it costs familiarity, not correctness.
Good for
- Diagnosing slow first loads
- Comparing before and after a change
- Showing stakeholders what a slow connection actually looks like
- Testing from a specific country or device
Watch out for
Results are lab data from one run on one connection profile. Use field data from real users to decide what to fix, and this to understand why it is slow.
Continue from here
Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.
Often used with
These usually appear in the same screen or the same decision.
- Doherty ThresholdLaw
- Loading StatesPattern
- Performance as User ExperienceUI foundation
Nearby in the Atlas
Adjacent territory, found through shared tags rather than a stated link.