Another serious help for me was found at Carsmasters light in IL-2 beta. Thread is in Visuals.
The mod itself helped quite a bit with FPS as well as making IL-2 look much better! the thread is a bit confusing but start at the beginning and read carefully and you should get it sorted

I'm fairly sure the latest one is: Carsmaster Light in the IL2 (beta)+1536 pix v.2.2.1.7z or you can look for: Carsmaster Light in the IL2 (ALPHA!!!) v.2.3 ALPHA !!! more 4Gb memory (there is a part for the mod/DBW/UP/SAS folder and new DLL's etc. for root of game.
Read the installs carefully, but if I could get it working anyone can

Buried somewhere in that thread is a download of Carsmasters Nvidia inspector settings, grab that, download Nvidia Inspector and apply ALL his settings excactly, i was very surprised and pleased with the results

you could maybe later bump up the AA and AS ( i run AA 8xS [Combined: 1x2 SS + 4x MS] and 16X AS with no real loss in FPS, but try his settings first

A full uninstall of videocard drivers and fresh clean install of the latest ones can have a good effect as well, i was sceptical but it helped me
Cheers Dakpilot
**EDIT** I would have a quick try of Gurners latest effect mod, really nice with good FPS
