As anecdotal evidence, their results seem to be indicative of the real-world browser performance I'm seeing with my (largish) application. There is a perceptible difference between Safari, Chrome and Firefox, in that order.
I really hope that Firefox catches up with JavaScript performance, BTW.
lazyweb: arewefastyet.com from mozilla used to visualize performance differences between chrome, safari/webkit and firefox. Safari used to come out on top. Is this still the case? Is there perhaps another site where one can follow these browser races?
Safari doesn't run on Linux and hasn't supported Windows in a long time. Opera and Edge have or are switching to be Chromium based. iOS doesn't allow apps to implement performant browser engines so they all skin Safari.
Technically you could load Firefox, Chrome, and Safari on Mac but Firefox and Chrome have wildly different performance on the same hardware running on Mac vs Windows.
So in short no, there aren't really any useful comparisons to be had beyond what arewefastyet currently has.
A lot of this article is about benchmark construction methodology and performance optimizations. If you just want to see a cross-browser JavaScript performance comparison, scroll to the bottom.
I really hope that Firefox catches up with JavaScript performance, BTW.