Have a huge LAG after one hour of flight

i got smiliar problem after playing couple of missions the loading times are increasing sometimes some missions are impossible to play without restarting computer probably memory issue

Bet my left nut it's the GPU. Your new one is gonna fix everything and increase your sex life!

Might also be temperature related, GFX card needs to work very hard and eventually throttles down, causing lower FPS. It might even shut down if it reaches a critical temperature?

I am using a GTX650 (i-5, 8GB mem.) and playing with 1440x900 res, mid graphics settings.

Getting around 60 fps (down to 30 near big cities), but not much lag.

Rokomah, You can try-out using lower res., moving your way up as you notice improvement.