

One thing you’ll often see is that “new” browsers - i.e. with no browser history, extensions, etc. - perform better than one you’ve been using for a while. Thus, when people switch browsers, the new one tends to feel faster, regardless of what you’re switching to.
Possibly, Firefox feels just as fast after a refresh. Alternatively, a fresh profile using the new profile manager might do the same.
On the other hand, it could also be that that specific site has just been tested and optimised in Chrome, with Firefox mostly ignored because too few people use it :(
Sure. It could still be worth checking a fresh profile and installing those two extensions - it could still be faster.