GeForce III Ti 200 performance under linux

I have the above mentioned card installed on my computer i have both WinXp
and Linux Debian (Woody/Sarge/Sid).
When i run America's Army: Operations under WinXp it all goes fine, the
graphics are fast and of good quality, but when i run the same game under
Linux the graphics are good in closed spaces and when looking to the ground
but when moving the camera looking to big open spaces or to the sky the
movements are sensibly slower.

I have installed the nvidia driver (glx and module)
debian:/home/erix# lsmod | grep NV
NVdriver 945440 10

And obviously the graphic acceleration works, because the game is running at
a normal speed, but the performance is lower than the Windows one.
How can i fix this? I've set an AGP aperture size of 64 mega in my bios
settings.
Any help would be very appreciated.
--
bye
Erix http://erix.cjb.net