No problems with the video card under other circumstances... games, Maya, etc. After much experimentation, it appears that the hesitation only occurs under the following circumstances:

- Pan, zoom, or rotate a viewport. (Smooth!!! Instant updates.)

- Immediately move the cursor (ie. in one motion: release the mouse button after the viewport change and at the same time move the cursor).

- The cursor "sticks" for a second or so after the completion of the view change.

It's almost as if MoI is intensely busy for a very short interval immediately after the view change.

Not a big deal, though. I can work (uh, play!) around this issue by changing my behavior just a wee bit.