Same as with large SW models;
Create configs or Display States showing smaller sub-assys which can be viewed seperately, and make sure that smaller (less important) details and components are suppressed when the full assy must be shown.
Edrawings is just a viewer and with a viewer comes limitations. If you are having troubles viewing the item in edrawings it could be the VC or display driver that makes it run slow. There is not much you can do about that. You can try the SW viewer, but then again the plan is to phase that out... of course I have been told that for 3 years now and its still being released.