Just upgraded to the new Firefox 13 minutes ago. Mozilla did it!
Firefox 13 is faster to start and smooth to configure and close. I am using Firefox 13 in GNOME 3.4, Arch Linux. I have a 32-bit linux kernel 3.3.7. As always I have NoScript 2.4.3 ( I have yet to upgrade to NoScript 2.4.4), HTTPS Everywhere and Better Privacy enabled.