If you run ‘htop’ you might see over 60 processes named ‘console-kit-daemon’. This seems to be a bug. On a mostly-single-user system one might as well uninstall ‘consolekit’ package (seems to be used for fast user switching).
For more see:
http://ubuntuforums.org/showpost.php?p=3609863&postcount=10
P.S. Alas, some other packages depend on ‘consolekit’; not removing for now.