it will drop some in the heavy furballs and smoke but with a good 64mb vc it should only drop 10-15 fps ,the lantency of all the players in one area effect this also ...
A 56k connect can effect this also ..
you can try a video setting of 800x600 16bit , ctrl C toggles ground clutter , shift f1, shift f2 , and shift f3 , changes the visiability range from full, med, short .
try a few different settings until you get the best frame rate .