DM_GasworksInc too slow outside... need your help!

I fear that all of my hours gone into this map will be for naught if I can't inrease the speed of the map in the outside area. Most of the time it's fine, but in the corners (where you can obviously see more stuff) it gets slow.

I don't have any areaportals or occluders but I don't think I can use them because the area is so opened up... I've also enabled the fade distance on models so that they fade out, which definitely helps, but it doesn't see like enough.

Lastly, the entire non-playable outside area is NOT a 3D Skybox yet... do you think that it could be a major slowdown in things? Please let me know if you have any ideas.

http://www.snarkpit.com/maps.php?map=1602

get that to 3d sky box ASAP that should help alot, infact I dare say it would make the out side 1/16 as big!

Almost done.. also found out that the tree models I was using were very slow... not the complicated mesh models, I'm talking about the cheasy transparent texture looking ones... yikes, who'd knw they'd be that slow?

even me sometimes my outside area lags...but i dunno how to fix it lol...