I have been getting the spinning ball of death with frustrating frequency. I began to notice that it occured most when I would peruse the edit by dragging the cursor along the timeline. I then also noticed that I got a short duration spinner when I would make some intricate audio moves. That made me wonder about the expanded track display on the mixer. Happily, I'm working on a rock vid, so I'm not always doing extensive audio work.
I notice that if I take the mixer offline, the spinning ball either diminishes or disappears. And I can drag the timeline as of old. Perhaps the new track display is quite RAM intensive. Something to address on the dot fix, maybe?
In retrospect, I wish I was not as aggressive with the new upgrade given that it came with a new OS X. Quite a few operational considerations.
I'm rating the current at a 50/50 with the pluses a real plus and the negatives very disconcerting.