I've been using FF as my main browser again since (I think) Quantum, and kept it at version 91 to avoid the constant breaking UI changes. Performance since Quantum is generally good, but for more intense things like video or apps I am going back to Chrome now. FF keeps my CPU 20C higher than Chrome for some simple Youtube videos, which is just ridiculous (Macbook 12, 2017).

For daily non-performance relevant use, I still like the Container feature a lot though, doesn't look like Chrome will get it anytime soon.