Did you do a wipe before installing? I had lag issues as well. I did a clean install and downgraded to Launcherpro 0.4.4 and there's no more lag. If there's ever redraw w/ Launcherpro, it literally takes no more than 1 second.
I also switched to P3Droid LV 1.2ghz, that may have done something too..
I'm running BB .4 with launcherpro updated version and P3Droid 1k mhz lv kernal. I haven't experienced any lag with this set up. Did you wipe when you first installed? If you don't know whats causing it, I would just reinstall the rom and remember to wipe 3x.