Ok, here's a weird one for you. Maybe someone can shed some light on this for me. I now have a work around, but the why would be nice to know. I start out with some import geometry, 4 curves from Adobe Illustrator. Create 4 sketches, nothing complex, no splines, just multiple segment, tangent arcs. My file size is about 500kbytes. Create a VSS using one of the curves as the traj. and a single arc as the section (since it was simple I also used insert:sweep:surface - same issue) file size jumps to 2 megbytes. Create a second VSS similar type as first one, project a curve onto the 2nd VSS - boom - file size is now 10megbytes, and very sluggish on my workstation. Ugh. and I only have 16 features, of which only two I would consider relatively complex. Get frustrated, try a few different things to avoid this rot. Shut down, go get a latte, start a new model, leave out the imported geometry, create the same stuff (now that all the dims are memorized from trying them so many times) and the file size is slightly under 600kbytes, with additional features. So, this import geometry wasn't being referenced, it was only being used as tracing paper, but was causing all kinds of calculational stuff in the background. Anyone else seen this? Thanks Dave.