Sadly there must be more to it too though, as even with an I7 930 @4.2ghz and 6gb of DDR3 RAM @1600mhz my AI frequently fails to engage the enemy in clear sight, especially when they're in vehicles.
The campaign is almost unplayable because of this too, I was recently replaying the ArmA 2 one and in every single mission at some point one or all of my squad members would simply stop responding to any commands and stop moving.
Biggest thing on my ArmA 3 wishlist is a hugely improved AI, as well as being able to play multiplayer without horrendous lag.
