This has absolutely not been my experience. Must be a different extension you installed.
Or I just visit different websites?
Not the worst idea to avoid a website for breaking in FF (or take a chance to touch grass), but unfortunately when you can't pay your credit card bill or need something for your work and it only works in Chromium it can't be avoided.
Then we can compare brave and firefox in terms of speed. I don’t see any noticeable performance difference (I use both on linux and macos)
Then ... maybe have a look at some numbers:
https://www.phoronix.com/news/Firefox-Chrome-109-Benchmarks
And sadly it can be worse, with my quite complex app, that I absolutely did not tailor for chrome, but gone out of my way to also support FF - the result is that chrome is just 3x faster.
I regulary ran across something that does not work or has a broken style. And I know how to turn UO off.
And why should that be a surprise? FF has way less manpower than Chrome. (And even fired lots of engineers, to raise the CEO bonus)
Chrome leads the way and probably the vast majority developes for chrome and with chrome dev tools. So most of the time FF works, but not always. And performance is just worse, but not noticable on a desktop and on mobile it is offset by the working adblock. Meaning perceived performance is usually better, because ads are blocked, unlike in chrome mobile.