For me, on a win 8.1, i7 computer, it's roughly the same speed. I was using html5 because hey, that's more modern, that's the way to go. Then I frequently had to log in from a smaller linux computer as well, html5 there is just terrible. It's totally unusable. I switched to flash there. That's okay. Of course, this changed my preference to flash on my main computer as well (bah...
), and that's when I noticed that wow, even on an i7, flash is somewhat faster. Not by much, html5 would be totally usable there, but flash is still faster. And since I don't want to keep changing my preference each time, I'm stuck with flash.