"Terrain complexity level. Sliding this bar to the Right will increase the
complexity of the outer lines of scenery shapes. This will improve visual
quality (more realistic terrain), although performance may be reduced as a
result. The further the slider bar to the Left the simpler terrain textures
will appear (Less complex shapes), although performance will improve in such
Max. object texture size. Moving this slider to the Right (Higher) will
allow the use of sharper textures in the game for objects, although
performance can be lowered (Especially on low memory graphics cards). The
Lower this setting the more blurred textures will appear in the game.
Selecting a lower setting can improve performance on graphics cards with low
video memory. NOTE - Some graphics cards have a limit on maximum texture
resolution, e.g. with 3dfx cards older than the Voodoo 4 cards you shouldn't
set this above 256 as its limited to 256*256 texture sizes. "
FULL STORY @ 3DSPOTLIGHT (http://www.3dspotlight.com/tweaks/cfs2/index.shtml)