Quote - Do you have Enable Harware Shading on in the preview settings? If yes, switch it off for this scene and see if things speed up.

I did have it enabled.  Disabling it helped.

Quote - I'm sure you've tried switching between the PBuffer and Scene Window, if not give that a try.

Already using Scene Window.

Quote - There also is the Preview texture resolution slider. With this being one huge prop, I would set it lower then usual, that could speed up things a lot.

And now we're cookin'.  Disabling hardware shading and sliding the texture resolution all the way to the left did the trick.

Thanks!  :D

Quote - ... of course the preview window won't look quite as good as before after disabeling the hardware shading, but the speed boost is quite noticeable.

I don't render in Poser anyway, so that's not a concern.  My workflow uses Reality/Lux.