Firefox on android has genuinely become decent af and quite quick. I've been reporting a view bugs i've had on android and it seemed the GPU on some phones was causing stuter. They've solved all of that .
Still some basic features I wish they had though (Tab stacking plz)
On my phone the new firefox for android is much, much slower than the old one, even though it rarely has any tabs open (because I barely use it). Old firefox with a few dozen tabs is much more performant for me.