I just wish they finally fixed the bug that makes it unusable for me and thousands of other users using macbooks with resolution set to "more space"... I can't count how many people in my office I've had to help after their macbook randomly starts heating and turning fans to max power, it's always that they started using firefox.
I've been checking the tickets associated with the issue (mainly [this one](https://bugzilla.mozilla.org/show_bug.cgi?id=1404042) ) and there doesn't seem to be any significant advance, nor it seems the people in charge are aware of how prevalent and deal breaking this bug is :(