You can add me to the list.
I got a Q6600 OC'ed to 3.5GHz, with a GTX 670 running at 1200MHz. The problem exists with me where I have low cpu usage and in turn my GTX 670 is not used to its full capacity. I get ~20 fps with settings turned high but not ultra.
Moreover, As I play longer and longer, the game just becomes slower and slower. At one point, playing MP, I got down to 9-11FPS, so I turned down everything to low, lowered the resolution to 1280x768 from 1920X1200, and the FPS did not change.
I doubt that this is a problem with my hardware, as every other game does take advantage of everything I have.
ARMA II did that btw, so whatever that was copied over to ARMA III included whatever problem I, and many other on here seem to be having.
I used CPU affinity to make ARMA III use 2 cores, instead of all cores, and the fps did not change meaning 2 cores arn't even being used. I tried all the perameters that were mentioned on this thread and I got no performance increase
My specs again:
Intel Q6600 2.4GHz @ 3.5GHz
GTX 670 2GB @ 1200 MHz
8GB 1066 DDR2 memory 5-5-5-15