After searching the cow I see this was an issue for some people 4-5 years ago; but in the past year or two it seems to have gone away.
When I drag through the timeline it sticks at various random points.
My pertinent fact:
2x2.8 G Mac Pro
ATI 4870 graphics card
8 gig of paired and properly installed RAM
CalDigit HDONE showing 350-400 MB/s read/writes
1920x1080i sequence. All media is 1920x1080i ProRess 422 plus various stills.
Big Timeline 1.5 hours.
The system was flying for this whole project up until yesterday. Trying to figure out what I am doing different that is causing this.
Thanks Jerry, I think I got it figured out. I had some audio that was sent to me at 32 bit!!! I did not know there even was such a thing. Amazing FCP worked at all. Things are much better once I converted it to 16 bit and cut it back in.