Flight Enviroment question

I've been using Flight 1's Flight Enviroment for a few weeks now and over all I like it very much. But overcast conditions and rain just kill, and I mean kill my frame rates. My question is what cloud settings work best for those overcast conditons?? I have played around with a few but can't seem to come up with a descent solution. When I am on top the frame rates are fine, it's just on the ground and raining.Any help would be greatly appreciated.