I've got an I7 with an ATI 4870 and the game stutters badly. It's weird because between the stuttering the frame rate is very high.
I guess the game is doing something every 1 sec or so that is causing it to stutter. The question is, is it the game doing this or the constant communications with Ubi?
Right now the stuttering makes the game unplayable for me because it breaks immersion. This is especially the case on the upper deck where the waves kind of stutter along.
Speaking of waves I did a mission in rough seas and inside the sub it was hardly rocking at all. In SH3 you would be in for a much more rocky ride.
Going back to the subject in hand, even setting my graphics to minimum I still get stuttering with no real change in framerate. There is something about the programming of this game or the DRM which is causing this, which I'm beginning to suspect has nothing to do with the graphics...