We were talking the other day about the Forest= setting. Setting it to 3 makes the trees look better, more rounded and they are animated so they appear to sway in the wind.
This is Forest=2

This is Forest=3

Normally with these settings the higher you go, the more of a framerate hit you take. But strangely enough I've actually found slightly better performance with the higher forest setting, particularly on maps like those Slovakia ones which sometimes get a little nasty on the frames. Anyways, its something to try and see if it benefits you or not.
As usual make sure you edit the Forest= entry in the proper area of the conf.ini, DirectX or OpenGL, depending on what you are using.
DW