Obviously the most frustrating delay is the gun's. It perfectly ruins the aiming. But the flight controls are also very annoying. First i thought that it is only some strange presentation of the ac's inertia, but when i looked at the virtual control column i could see that it moves with a delay compared to my joystick.
Anyway reducing the frame buffer is a good point, I would give it a try. Where should i adjust it? Is it some game setting in conf.ini, or is it a general vidcard setting?