I would suggest trying the freeze track option. I think you will find it doesn't interfere with your workflow in any majorly disruptive way, and it should free up some resources, to the best of my knowledge. (I have giant bunches of memory, so I don't tend to freeze things).
Give that a shot - if you are not currently a Sonar user, try the available download and give that a shot. You have 30 days to play around with it. I think the current download that is out there is still X2, but that should still be fine.
Bob Bone