Install
Watchdog and see what's using a lot of cpu or memory. It told me my email was using a lot of cpu and I rebooted and haven't seen it since.
O/W you could note what apps you have on your screens (and where) and remove them and see if that fixes the problem, then add them one at a time until the problem comes back. A better solution, if you're rooted, would be to back up your current config to a nandroid with
CW Recovery and
Rom Manager while you play. Then if you hose something you have a backup.
OTOH, if you're getting FC's, I'd switch back to Blur with Home Switcher, uninstall LP, clear the cache partition and dalvik cache (if you have recovery installed), reinstall LP. You might even need to do a system reset, but that means having to reinstall/setup everything again so you'd want to try everything else first.
FWIW, these are my LPP advanced memory settings:
Memory preset: high
Use homescreen caches: checked
Cache type: normal
Build, clear and Prevent FC's are all unchecked.