see my post a few spots up where I link to the XDA Developer Forum Thread in regards to the lag fix. It's literally as simple as running a .bat file.
The lag fix uses a 1GB EXT2 virtual partition within the phone's existing 2gb of internal RFS storage for caching data and dalvik-cache. You do lose 1GB of app storage with this "fix", but to be quite honest our phones have a ridiculously huge amount of app storage space relative to other Android OS phone. I'm on my 7th page of apps in the Twiz app drawer and probably have enough app storage to double that amount still.
The benefits are less apparent than the monstrous increase in Quadrant benchmark score would indicate, but the phone is overall far smoother with no home screen, app drawer, or app launch lag whatsoever now.
It's easy to do, and just as easy to undo. Batch files for a simple one-click do/un-do are included in the XDA Dev post I linked. Though it is a painfully simple fix for the lag issues, PLEASE be sure to read the entire OP post and the thread in total before you do this, just to avoid any gotchas you may encounter if you have done any other mods to your phone.
I myself am basically stock, merely rooted. Best of luck!