Page load time is an important aspect of performance, but it’s not the only one. After a site has loaded, it should respond quickly to clicks, taps, and keypresses. But this can be difficult to measure and optimize.
I’ll talk about the Event Timing API and how it can be used to measure interaction timings in RUM analytics and lab tooling. Then I’ll dig deeper into understanding where the time is going, breaking down the problems that end users are seeing and reproducing them in the lab.
Finally I’ll talk about some common problems my team and I have seen as we’ve dug into how responsive web sites are to user interactions, and how to avoid them.