Do you have some good examples of how this "real world" perf if tested?

I often write micro benchmarks to see if something is faster one way or another. I often find one browser or another to be 3x to 10x faster in a certain micro benchmark.

A big issue is, most websites don't need perf AFAICT. Of the sites I use regularly (HN, Stack Overflow, GMail, Gdocs, GSheets, Facebook, Messenger, Slack, Reddit, github, maybe only gsheets and gdocs need any real perf.

The place where perf is needed is things like three.js, playcanvas, babylon.js, unity -> html, etc... And on those AFAIK, Chrome almost always wins, probably, because it's GPU support is multi-process