I've followed Mozilla.org since the project was first announced in 1998, and I've been a Mac OS X user since 2004.<p>Unfortunately, they've routinely shipped OS X versions of Firefox with show stoppingly-bad performance and UI bugs, and they've been far too conservative in addressing such issues. For years I rolled my own builds of Firefox just to include patches for important bugs that had been left languishing in bugzilla. (I see they finally fixed horizontal scrolling, only 7 years after two-finger scrolling was first introduced. Nice.)<p>As soon as Safari was able to match Firefox's performance, which was about 5 years ago, I left Firefox behind for good. Firefox was always, and probably still is, a fine browser on Windows, but the OS X version of Firefox is second class and really only suitable for Firefox superfans.