Arma 2 CO running slow

I have just built a new gamming desktop with a gtx 680 and I ran standard Arma 2 and benchmarked it with full settings and got an average of 42 fps. I then benchmarked CO and am getting 21 fps. I am using windows 8. Can someone please help me fix this problem and please dont tell me to get windows 7 if there is no solution just tell me please.

What CPU are you using, and if it's not that it's most likely one of the many poorly optimized games for windows 8.

Unfortunately that does sound like it might be because you have windows 8.

I have an i7 3770K and I was thinking the OS might be the case but I was confused because I was getting high frames in standard Arma 2.