I've recently run into some problems with the current terrain system, and am wondering if I can do anything about it. I normally create a terrain with standard brushes, but when I add noise effects to deform it, I end up getting about 20 FPS drop in framerate when the characters looks at the terrain. I ran various tests for both enclosed situation, and open. To me this would seem like the current terrain has too many vertices/polys/etc. Anyone else had this issue in drastic framerate drop before? I don't seem to have this issue with lots of models, but the terrain itself is what tends to lower the framerate. If anyone has any idea on how to optimize this, or what to do in this case, that would be great.

Our current game will be based mostly in the open terrain, with some interiors, so having really detailed mountains would be a must for us.

you can use heightmap in low quality mode (world editor\menu\heightmap\low quality)