NVIDIA Driver on FC4 - performance?

Installed ok once you turn off selinux, however performance seems poorer.  Here is a strange story
I posted to the NVIDIA linux forum, but noone has replied so maybe someone here can cast some light.
I upgraded my machine from FC3 to FC4 via yum, all worked well and I decided for grins to install the nvidia
drivers so I could use the GLSlideShow screensaver (shallow I know).  The screensaver worked flawlessly.
I then did a clean install on the same machine and after disabling selinux installed the same drivers now the
GLSlideShow screensaver is choppy as thought here is a timing problem (black bands strobing across the display
as the image is panned and zoomed).  No combination of the parameters in the nvidia-settings seems to improve
matters.  The card is a GeForce 4400 MX 64Mbyte with 8xAGP.  The system is a Dell Optiplex 270.  The monitor is a
Dell 17" flat panel driven via DVI.  The display is set to 60  VerticalRefresh wich is the panels optimum.

I don't mean to hijack the thread :)