However, Migration Assistant did migrate some stuff that I wished it hadn’t. After I got up and running, I was still noticing the occasional slowdown (and the appearance of the hated spinning pinwheel of death). Clued in by my wise boss, Rick LePage, I popped open the Console utility and discovered approximately a zillion error messages, most of them attributed to items in my /Library/InputManagers and ~/Library/InputManagers folders. I tossed those items overboard (goodbye, Menu Extra Enabler, SIMBL, Smart Crash Reports, and Chax!), pruned my PreferencePanes folders as well, and everything seemed to stabilize. I can’t say for sure if those items were truly causing slowdowns, but starting fresh certainly seemed to help. (In related news, MacFixIt reports that Migration Assistant also brings over unwanted PowerPC printer drivers. So beware.)