How Chrome Measures Performance

Chrome collects performance data both in the lab and from end users. There are thousands of individual metrics. This is an overview of how to sort through them at a high level.

Domain Areas

At a high level, performance work in Chrome is categorized into domains, like loading, memory, and power. Each domain has critical laboratory and end-user metrics associated with it.

  • An overview of domains: lists the domains and key contact points.
  • Speed Launch Metrics: the important high-level end-user metrics we measure for each domain.
  • TODO: Link to documentation on critical laboratory measurements for each domain.

Laboratory Metrics

Chrome has multiple performance labs in which benchmarks are run on continuous builds to pinpoint performance regressions down to individual changelists.

The chrome.perf lab

The main lab for performance monitoring is chrome.perf. It continuously tests chromium commits and is monitored by several perf sheriff rotations.

Other performance labs

There are several other performance labs for specialized use:

End-user metrics

The Speed Launch Metrics doc explains metrics available in UMA for end user performance. If you want to test how your change impacts these metrics for end users, you‘ll probably want to Run a Finch Trial (Googlers only). If you want to run a trial and are not a Googler, you’ll need a Google-internal partner to help you run it.

The UMA Sampling Profiler (Googlers only) measures Chrome execution using statistical profiling, producing aggregate execution profiles across the function call tree. The profiler is useful for understanding how your code performs for end users, and the precise performance impact of code changes.