I noticed a reduction in lag when I cleared my cache. Just go to settings, applications, manage applications. Press menu and click "sort by size" Clear the cache for your photo album and browser and any other large apps (1mb+). Also clear your call history every so often. (click phone, menu, call history, menu and delete all) Combined with a daily task kill, weekly phone restart and removal of unused apps, and you should notice less lag on the phone.