- You as the developer need to manage the shape objects on the map. Only show what's necessary in your given view. For example, if you are looking at a map of the united states, don't try to draw county polygons for a given state. Only draw county polygons when you have zoomed in to a level where it would make sense. After you have zoomed in, you need to clear any polygons outside the current map view.
If using something like MapDotNet isn't an option for you and you need to go down the "do it yourself" path, then you'll want to check a post from Keith Kinnan I just came across titled Microsoft Research Releases Tiled Vectors Demo. There's some great information and code samples for you "doityourselfers."