Ubuntu 8.04.1 rotate screen 90 degrees

[James Den Kaat]

I have installed Ubuntu 8.04.1 on an atom motherboard with an Intel 
945gm graphics on board. I have installed the latest intel drivers and 
al is fine in normal mode. However, I have a requirement to run the 
screen in portrait mode, that is at 90 degrees, when I do this 
everything slows down to a crawl.

Is there any way to improve performance so that it gives a similar 
result no matter how I rotate the screen?

Thank You

J DenKaat