Would using 'hints' and func_wall brushes help over come this? What about stretching the textures on the cliff faces to twice the size (I have no idea how to do that though)?
i did away with the fog/cloud effects but no dice; the tree model has a deceivingly low poly count =)
Any help would be appreciative.
PS: This is my first map and it took about 6 hours
Here are some Editor Screenys:




Full compile Log: