I too, have noticed system slow-downs in Tiger if it hasn't been rebooted in more than about 5 or 6 days. I checked my activity monitor, and my weather and stock widgets are now using more than 70 megs of real RAM! Also, my VM size is more than 5 gigs (is this normal? I have just "normal" programs open, mail, safari, ichat, itunes, ical, and 768 MB of RAM). I have definitely noticed more disk thrashing under Tiger than in Panther.