Hi Burr, and probably not so much about 4 times as many pixels to draw, but rather 4 times as many pixels to read back from the card to do hit testing.

Every time you move the view a new set of hit test information has to be read back from the card the next time you do some action with the mouse that needs to do some operation that targets objects like selection or hit testing. So by doing that type of thing where you're changing the view and simultaneously using the mouse you're getting a whole lot of hit test map recalculations which means a lot of stuff needs to come from the card into main memory - some video cards are not very speedy at pulling things in that direction.

Do you have a pretty new video card on this particular machine?

- Michael