Motion is so slow - spinning ball all the time!

Question

I took a class in Motion recently and they used iMacs at every station.  I never got a spinning ball.  I've got a 12 Core with 16GB of RAM and I can't scroll a window without getting a spinning ball.  Every tiny adjustment takes forever!  Another thing, when I select an effect or track, sometimes the HUD doesn't update until I click around a bit.  Just now it's started holding a single frame of video regardless where I put the scrub bar on the timeline.  The motion tracked box moves when I scrub but the picture beneath is a freeze frame.  Wait, I take that back, it seems to be playing at 1 frame per minute.  This is not a complicated composite either.  One shot with a motion tracked TIFF file on top.
I've restarted, checked permisisons, trashed preferences.  Nothing helps. 
I'm editing HDV.  I'm using internal drives for all media and applications (different internal drives).  All my software is up to date.  Is there anything I should check?  Any settings?  Any likely culprits?
TIA,
Pete

Answer 1

To Michael's checklist I'd add this: are you using the download version of Motion? If you are, it's possible there may be some sort of conflict with FCS. If you're still getting beachballs, consider reinstalling Motion…using Apple's "best installation practices".
I too don't like to work in HDV, but on the occasions I have, I've not encountered anywhere near the difficulties you describe.
Russ