On my machine, Firefox got 12.3, and Edge (Chromium) got 12.8. I don't believe that the performance characteristics of these two are that close unless I'm missing something. For example, audio players on Edge stutter a lot while Firefox plays them smoothly. An example is:
https://deepsid.chordian.net/ I believe Edge is slower not because Chromium is slow, but because of Microsoft's overreaching efforts on energy conservation.
Machine: AMD 5950X, 32GB RAM, 3080 GPU, Windows 11 Pro 23H2
Firefox v123.0.1
Edge v122.0.2365.80
EDIT: Interesting, I tried both in private windows later to bypass extensions, and Edge got 10.8 this time, Firefox got 16.9. I now have more questions.