Follow this guide to tweak and fix ArmA II for best performance.
I changed the settings accordingly and damn if it aint great. I have a 27" 1920x1200 monitor at 16:10 ratio so I set my Horizontal FOV to 100 which gave me 74 vertical FOV. then I converted it to radians 1.29. This is my FoVTop.
Divided it by 1200 or 10, then multiplied by 1920 or 16 and rounded it to 2 places after the decimal. that was my FoVLeft.
Changed my mouseSmoothing setting from 30 to 1 made a big difference as everything is smoother feeling now.