deleted and reinstalled MF a couple times now, shut down and restarted the ipad a couple times now, i have really no music on my 32g ipad 3 (so more than half the memory is free), and nothing i'm aware of is running in the background (certainly no more than five days ago when i last used a perfectly zippy MF2).
i guess "unusable" is an exaggeration, i'll just go with "sucks", not exactly what i wanted from the big, much-awaited upgrade.