Does the GFX card or the CPU dictate the speed you move...

Does the GFX card or the CPU dictate the speed you move around the screen in a project? for example once my projects start getting quite dense panning around the project window just gets slower and slower… also moving between the mixer views just gets slower…

i just wondered if this is actually limited by the graphics card ? with it being 2d and not 3d I wasnt too sure…

Can do but is usually graphics card driver related. Update the driver or try reverting to an earlier one if the problem started after an update.
If your problem usually involves zoom then there are a couple of threads on this. Not too sure but I think Cubase 6.0.2 or 6.0.3 might have addressed this.