Are you using a lot of hardware (does the hardware have detailed threads?) if so then create a configuration in the hardware part files to supress the detailed features. This should speed things up a lot.
THE BEST APROACH TO THIS IS TO CREATE A SEPERATE CONFIGURATION IN THE ASSEMBLY AND SHOW THE HIDDEN PART
THEN YOU SHOULD REFERENCE THE CONFIGURATION IN THE DRAWING FILE
The 32meg Elsa Gladiac video card has worked extreamly well for me (You may have to hit the rebuild button more than if you were using a better card but it works well.