1.Set your log duration to 1 day or No log if possible. Works wonders!
Normally, the call log list defaults to 30 days, but that's completely
unnecessary, at least from our speed point of view.
Open up the Log application, hit options (left softkey), and select the
Settings option. Change the Log duration to (optimally) 1 day or No log
if possible. Either way, it should give you a noticeable speed increase.
2.Delete install log.. See my Screeshots..
3.Delete media log... Follow Screenshots..
4.Finally, keep your phone's firmware updated! All right, that was a
cheap one. But seriously, sometimes Nokia actually improves the user
interface a bit - take the latest N95 firmware, for example, which
speeds up the Gallery by removing the mean bug that caused the gallery
menu to appear for a second or two before (slowly) sliding off the
screen.