We really need some kind of optimization setting available which will improve the performance of OpenRoads when Existing Ground Terrain Contours are Displayed. I believe this setting in Civil 3D is called "Level of Detail" or something. The problem is that when we have Existing Ground Terrains covering large areas with contours displayed, the performance is Drastically Reduced. Performance is much better if a Feature Definition is used which Only Displays the terrain boundary (or create a clipped terrain etc.), but there are Many cases where we need to work with the full set of contours displayed, such as road/site layout as well as when creating drawings, we need the contours turned on which makes it almost impossible to work. Zooming in and out as well as panning around etc. becomes very very very slow and laggy. It should also be noted that if the contours are extracted to Regular MicroStation Graphics, then the performance is totally fine, so hopefully a setting can be added to display terrains as regular graphics or something so it can still be used for design etc. which you cannot do from extracted contours.