A present PC cannot handle all the polygons in IL2.
In a city with many, many buildings, the use of the GPU (video Card) can be of 10%.
But your CPU generates a FPS fall, if you have intel I7 also you get FPS fall.
The number of polygons causes fear to me.
DX11 Tessellation, CPU multi-threading‎, CUDA and others new technology maybe make all more easy
I am not programmer,
But Everything is into the hands of the motor of BOB. maybe...
I find this site
http://heinkill.webs.com/stormofwarnews.htm
Have a screen shot FPS AVG 14 FPS. over sea.
Sorry for my bad english