When you close all your windows and firefox would normally exit, this is a perfect time to Restart firefox before minimizing it to the tray when it comes back up. It should be the session-preserving restart like the one offered by the add-on manager (or by justin Ƨullivan's "Restart Firefox" addon but not most others), so it preserves tabs and also session cookies, etc. The benefit is that it clears out unneeded memory from firefox and it often runs more smoothly than if you've been keeping it running continuously.
When you close all your windows and firefox would normally exit, this is a perfect time to Restart firefox before minimizing it to the tray when it comes back up. It should be the session-preserving restart like the one offered by the add-on manager (or by justin Ƨullivan's "Restart Firefox" addon but not most others), so it preserves tabs and also session cookies, etc. The benefit is that it clears out unneeded memory from firefox and it often runs more smoothly than if you've been keeping it running continuously.