Dunno if a thread exists for this already... I find that after I applied the latest update to Panther (i think it is 10.3.3) it has slowed down noticeably. I can actually measure Fast User Switching takes 5-6 seconds for each switch while it took a fraction earlier. The 'bouncing icon' on the dock is also for more time than before for a number of other apps. I have to say, I used the un-updated Panther just for a day, and then updated using the auto-update. Maybe I should not have updated...?