Weird. I have no problems with Firefox with youtube or anywhere else, everythings fine and dandy and it just zips along. I much prefer its fully featured extentions and there are only one or two basic equivalents for chrome.
This is my desktop PC though. I use Chrome on my lappy as it seems just a tad more responsive, slow performance in general is not an issue on my desktop, unlike the laptop. Chrome's tool bar doesn't take up half the lappy's 15" screen either.