Comment 2 for bug 400863

This was supposedly fixed by consolekit 0.3.0-2ubuntu7 by adding log rotation to the ConsoleKit history file:

consolekit (0.3.0-2ubuntu7) karmic; urgency=low

  * Install a logrotate configuration file for /var/log/ConsoleKit/history
    so that it doesn't get huge and cause ck-history to take a long while
    to run on login. ck-history already handles reading from rotated logs.

 -- James Westby Tue, 21 Jul 2009 10:41:19 +0100

We'll see if it actually addresses the issue sufficiently.