well, last time im posting regarding this. I did a last little play, and removed a couple of little things, and that improved performance yet again. but looking that the stats page as im running around, the main problem is static mesh tris. its much higher in areas than it should be according to that ut3 udn page. im no expert, but id guess that although your using around the limit in terms of amount of static meshes, static mesh tris is alot higher than acceptable, and in a couple of areas, nearly double, so im guessing its not the amount of meshes etc, but the amount of 'detailed' meshes in there. mixed with the lighting issues like the dynamic ones and the caustic water effects, i think the combination of it all is causing all the problems. i hope you can sort these things out and have a good play with it and try some of the things mentioned. at the moment, for me at around 5fps and thats without anyone else in there, its just not playable sadly.