Excessive CPU consumption when asking whether to update

[Michi Henning]

Every now and then, I notice my laptop sitting there doing nothing with the fans going full tilt. At those times, software updater shows me a prompt asking whether I want to install updates. Top shows:

   PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
 87294 michi 30 10 705080 131156 78876 S 18.1 3.3 32:02.85 update-manager
  1148 root 20 0 452256 135468 33220 S 10.6 3.4 58:13.24 Xorg

CPU consumption of update-manager is permanently around 20% while the dialog is displayed (see attachment), and Xorg eats another 10% or so. As soon as I dismiss the dialog, both update-manager and Xorg stop eating CPU.

This is really nasty, especially when I'm running on batteries and one of my VMs does this. The battery ends up empty in short order if the relevant VM is off-screen and I don't notice the hiss from the fans when I'm in a noisy environment.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.