Same problem here, 50-60% utilization on my cpu, and no more than 60% on my GPU, this is on a custom mission with 80 AI, maxed settings and vsync disabled.
Specs:
Intel i5 2500k @ 3.3ghz
Nvidia GTX460 SE running at 1280x1024

Driver v. 310.70

8gb DDR3 RAM
Win 7 64bit