Does CO 6.0 Pro regenerate KS preview image each time?

Well, I think I may have found out one of the causes why CO 6.0 Pro can be so sluggish at times. I created a new variant of an image, performed KS correction on one and just did slight rotation and cropping on the other. When I switched viewing between two, all 4 CPU cores shot up at 100% and nothing happened for about 3 seconds while the memory shot up too.

What is CO 6.0 doing at this time chewing up memory? There is no recalculation to be done. I was only switching the view from one variant to another. One possible guess would be that it is recreating preview images.

Has anyone encountered this?