BrowserLab: Automated regression detection for the web

What this post added

Introduced BrowserLab, an automated system for detecting client-side performance regressions in web applications. BrowserLab addresses noise sources like environment variance, dynamic data, and code non-determinism through techniques such as an HTTP proxy for isolating server noise, RAM disks and consistent browser states for reducing client environment noise, a backend proxy for consistent data views, and deterministic random number generation for code. It enables accurate measurement of regressions as small as 20 ms and provides root cause analysis via aggregated tracing data. The system is integrated into the continuous integration pipeline for automated regression detection and bisecting.