Thea Render --- Proxy Objects --- Tutorial #20
there is a way to replace the proxy geometry by any other object. Every single vertices and faces consume memory of ram, meaning that if you have several proxy in the scene, not only the Sketchup feedback is slower, but you could be wasting memory of ram needed to achieve a high resolution render. That is why it is a good idea to replace the actual low polygon proxy representation for an even more simpler geometry.