Even more puzzling why they haven`t taken advantage of it.
If what Brad/Frogboy has said on these forums is true, the AI engine in this game is pretty much unrivaled in terms of the power it can bring to bear. Most games don't bother doing AI the way it's being done here. They set up a nest of hard-coded scripts that the AI then follows and then they throw in some cheats wherever their testers determine that their AI deficiencies are glaringly obvious.
No game that I am aware of uses multiple cores the way GC3 does.
The weaknesses in GC3's AI are not a question of processing power. It's really about, do the people who are "teaching" the AI how to play the game actually know the best strategies? On release that answer was "Hhahahahaha! NO!" but the AI's been getting progressively better with the last two patches. It's still making some egregious mistakes (specifically, not defending its planets and setting its staging area in contested space -- which I think is the reason it marches its ships in piecemeal), but those will probably be pretty easy to fix. At that point I think "normal" difficulty will be pretty decent.