When a model has a very large amount of detail, SketchUp temporarily draws it as a skeleton so that you can see what is happening as you zoom, orbit, or pan. Then when you stop, it catches up and fills in the details. The onset of this behavior and the amount of time to recover depend on the complexity of the model and also the capabilities of your computer.
Thanks slbaumgartner.
I understand what you mean, but I believe this is a different issue. Have you had a look at the video link I posted?
After leaving the model for a while the geometry doesnt fill in the details.
Yes. DWG map files often have their origin at the origin of the map coordinate system used that can be thousands of kilometers away. In the worst case, the file has something (a point, line or block) to mark the origin, and you have to find and remove that too.