On OSX, Chrome works fine, until it's time to load up gif images, commonly found in the avatars and signatures of the forums I visit. Then I hit horrible lag and my temps go way up. Chrome becomes unresponsive.
It's fine on Firefox and Opera, but Chrome just seems to have some bugs (the OSX version) and so I'm torn, at times, on which one to use.
I use Chrome 99% of the time, despite that huge drawback, since I visit many forums. I have my Google Voice, Wave, and Reader notifier extensions that I love. I'm on the Firefox 4.0 beta 5 and the add-ons don't work on it. So that sways me a bit, as well, towards Chrome.