if ur ising 2.5/2.1 U can remove some graphics of the home tab manilla. i noticed a nice increase in speed and fluid animation in weather and sliding within the icons. when i removed things off the home screen. (top/bottom bars/appts background/clock background/icon backgrounds/etc. check out santods thread for home page mods. they are all uninstallable so no worries.
http://forum.ppcgeeks.com/showthread.php?t=101648
also for 2.1 try using HDWalls instead of BG4ALL. (HDWall is cab installed backgrounds) that increased my fluidness of the weather animations back when i was using mighty official 2.5 rom substantially.
thank me if this helps