I use Firefox for everyday use, but for HTML5 applications it stutters every few seconds making it extremely annoying and not a much enjoyable experience. Lately I'm having this issues with Youtube videos too and frequent random crashes.
I don't know if it's related to the latest updates or if it's my computer, but Chrome on the other hand gives me smooth results for all uses. I'm deeply considering switching to it for my everyday use since Firefox is starting to bother me.