more graphics on the screen more lag ull see when sliding. me have updated SW on our older slower HW. u can get around sliding from the home tab by maybe pressing the desired tab instead of sliding to it. (if its on screen of course.)
also try removing some graphics from the home screen. that free up some graphical resources. check out santods 2,5 mods thread
http://forum.ppcgeeks.com/showthread.php?t=101648 to remove things like clock background or the calendar background window, or the shortcut icon background shading, curtains, from the home tab screen.
good luck.