From README.Debian
"Users of some graphics cards may experience slowdowns because warzone2100
uses really big textures by default. You may be able to workaround this
by setting the texture size in the video options menu to 64 or 32. You can
also set this by adding textureSize=64 on a line in ~/.warzone2100-2.1/config"
From README.Debian 2.1/config"
"Users of some graphics cards may experience slowdowns because warzone2100
uses really big textures by default. You may be able to workaround this
by setting the texture size in the video options menu to 64 or 32. You can
also set this by adding textureSize=64 on a line in ~/.warzone2100-
Does setting texture to a lower size helps ?