Finally... after many hours of modelling in Revit, importing into 3DS Max, optimizing, importing into Sketchup and importing into Sandbox I finally scored a winning combination that didn't max out the polygon count or crash the computer. Its a small step but it shows that it can be done. It doesn't take long to max out the polygon count when modelling curves in Revit. I finally got it working by optimizing the geometry in 3DS Max,then splitting the model into segments in sketchup. Next time I want to try to maintain the quality of the geometry by not optimizing but reducing the extrusions to just planes in sketchup, hopefully reducing the number of polygons sufficiently.