Screen Redraw slow when full screen

[texynz]

I have just switched over to portals from having used fences for many years. Although I would consider I have quiet a few icons on my dual screen desktop, I did have this issue with fences. Basically if I play a game, and it goes into full screen on one of my monitors, if I happen move mouse outside of the screen space (even though its full screen not windowed full screen), my machine glitches a bit whilst it seems to redraw the icons on the desktop. It is like a 5-8 sec delay. I suspect observe the same when portals refreshes/caches the desktop. Is there anyway overcome this, otherwise portals seems to be doing what I require and plays nicely with the newer OS. Thanks