[vtkusers] Slow execution on Opteron

[Jeff Candy]

Execution speed for VTK 5.0.1 is really bad on my
dual Opteron 250 system.  Specifically, rendering a
single frame to a window appears to be a factor of
10 slower on a dual Opteron 250 (with nVidia NV34GL
Quadro FX 500/600) than on a P4 3.2Ghz system with
a Matrox G550.

Both platforms are running Suse 10.0.

Standard optimization flags, as in the ccmake tool,
make no difference.

Ideas?