Deus Gladiorum said:
ARMA games are infamously CPU intensive. However, try turning off V-Sync and see if that helps the issue. Also, try turning down your rendering distance. ARMA renders massive distances anyway, so you shouldn't need to kill your CPU by telling it to render even half as far as ARMA's maximum value.
V-Sync has always been off and my render distance is like 2000.