http://html5test.com/results/desktop.html
Honestly, most end users wouldn't know if their bum was on fire.
The long and short of it is... and the point I was trying to make(not well tho) is that Firefox is not the standard and it is certainly not the best. No browser is. Their performance changes so often.
I change browsers almost as often as I change underwear.
Many many years ago it was Netscape and Arachne(DOS browser) then it was Opera(until they started charging for it), then it was IE very briefly(I still shiver), FF for a long time but then FF started being really crap, was crashing on me and hogging resources(same symptoms on different systems) so it was time to jump ship again, Chrome for a while, then Opera again, then Chrome again...
Currently have three browsers installed (FF, Opera & Chrome) but use Opera most of the time, it just feels better to me and prints better than any other(currently), but man it sucks hard for Facebook. It has also just recently started garbling the playback controls on youtube.
I switch to chrome for FB and any flash content.
If I could pick what I want from each browser into one I'd be pretty happy.