I quit Firefox as soon as Chromium for Linux was available. My problem with Firefox wasn't so much the memory leaks (though those were annoying), but rather that it was SLOW. Opening new tabs caused the whole UI to grind to a halt while they rendered....and this wasn't on a slow computer. I've heard that FF has finally been multithreaded, but I haven't really tested it.

This isn't to say Chrome doesn't have its own memory or performance problems. GMail for example will eat up to 1GB of memory eventually before I notice I'm low. I have to actually close the tab (reloading doesn't fix it) and re-open it. It's "only" using 500MB right now...