A had the same issue. Started occurring regularly after the update. Took only a few minutes after relaunching the app for the CPU usage to hit 100%+ Took the prefs and a sample of the process through Activity Monitor and zipped them - http://stashbox.org/467430/utorrentprefs%2Bsample.zip Issue seems to be resolved at the moment though... edit: Alright, my bad. Hit 100% again, once a torrent finished downloading and started seeding.