Performance regressions in edge Rails versions happen quite often, and are sometimes introduced even by experienced Core commiters. The Rails team doesn’t have any tools to get notified about this kind of regressions yet. This is why I’ve built RailsPerf, a regression detection tool for Rails. It resembles a continuous integration service in a way: it runs benchmarks after every commit in Rails repo to detect any performance regressions. I will speak about building a right set of benchmarks, isolating build environments, and I will also analyze some performance graphs for major Rails versions.