Has your terrain brush got many flat coplanar polys ?
TerraEd if you are using the older version, the one I use... depending on your terrain you may have lots of flat joined polys...
I can get rid of these for you with a sentence or two...
Better for lighting if the many are made into one
per group that is.
Could you post up an in editor view of your main terrain brush highlighted from the 3d view, that would help...
Also if you post some small screens of your problem areas I am sure ppl will have some cool input to help reduce the visible poly count..
Remember throw some bots in... and ooopppps where's my fsp... or don't forget on-line playing,
I assume that this must help a server and of course the client-side players also.
Bastard'O