Well I'm running Firefox 36.0 stable 32 bit. It is running faster than CometBird but then again every time I do a fresh install of Firefox and it has empty folders to work with, it's snappy for about 2 weeks.
I hope this http/2 stuff is more than just smoke. As usual I can't seem to get it to accept SpeedDial FVD.
I haven't tried any of the YouTube html5 stuff yet.