1) What method are you using to add the pushpins? You are probably calling a geocode method (FindResults/FindAddressResults/GetLocation) over an iteration by looping or For..Next. You'll gain a lot of speed by first writing the new vehicle locations to a temporary file, and then using a bulk import (i.e. DataSets.ImportData) method to add them to the map. After the import you can iterate through the returned dataset to set pushpin properties such as BalloonState, etc.

2) You can minimize the mappoint windowstate during the pushpin drawing to avoid successive wm_paints.

3) Adding a pushpin does NOT actualy force/generate a ZoomTo, Union or GoTo. It must be somewhere in your code. However, using the DataSets.Import will make this point moot anyway.

HTH
Paul