If you change this in DayZ config to:
GPU_MaxFramesAhead=1;
you gain a lot more FPS (A LOT!).

I don't know why you use this param set on so high value.

My sugestion: This param should be default on val=1, but give players option to change it if someone like to have this on higher value. This doesn't change the gameplay, but give more satisfaction from playing DayZ :)