Now here is where it gets REALLY good: If you have TWO processors, or a DUAL core, then the SECOND CPU will load textures
while the FIRST CPU runs the simulator! Therefore, you can load scenery and fly at the SAME TIME, really lowering scenery-load pause times.
(Hint: to get the fastest load times from DSF, shut off roads and objects.

http://www.x-plane.com/