This always puzzles me too. I start firefox maybe twice a week across 2 or 3 machines, then just let it run until an OS update requires a reboot (or in some ca

This always puzzles me too. I start firefox maybe twice a week across 2 or 3 machines, then just let it run until an OS update requires a reboot (or in some cases when it's using > 1.5G of memory which is rare and may stop once I upgrade to ff15).