Doesn a 3D window server take up a lot more resources and run slower than the traditional 2D one?
No, but sometimes it depends. It is really more of a different performance paradigm more suited to the direction computer hardware is going. Situations can be conceived of in which the old paradigm might perform better, but in most situations Vision will run faster. Because Vision uses OpenGL for visualization it gains any hardware acceleration that OpenGL can take advantage of. Also using OpenGL commands to draw instead of copying pixel buffers has great benefits on todays systems.
