In 1.5.4: 109.6% CPU load (according to Activity Monitor) This is on 10.6.8, saving to a non-Spotlight-indexed folder (had trouble with MDS before), on an external usb-drive. Once the CPU usage went into overdrive, it was impossible to exit uTorrent without Force Close. Additionally, it did not seem as though it was successfully downloading/saving anything. After restarting uTorrent, CPU usage returned to ~20% and everything seems fine again. For now.