Yep... I just looked at the scene. I would start by disabling transparency and refraction for the water material. At this distance, it doesn't matter if the water is transparent or not. I would also break up the terrain into two pieces. One in the foreground, with bump enabled for the treee bark and the rocks. One in the background, with bump set to 0 for the tree back and the rocks. That should give you a good boost in performance.

• agiel - www.linfa.net