When uploading something at 200–400 KB/s µTorrent uses 20–30% of CPU. I have disabled encryption, diskio.flush_files — nothing helps. Even being idle, with totally disabled network, µTorrent uses 7–15% of CPU time! Due to that my MBP is always hot and noisy when µTorrent is launched... VLC, for instance, when playing a DivX movie (x1600 GPU, no hardware DivX decoder), uses only 7–8% of CPU.