Over the past couple of days, Kontact and gradually become so slow as to be unusable. New mail arrives, but whenever I click on an unread item, I see the message viewing pane turn blue and display "Retrieving Folder Contents, please wait..." and I wait, and I wait, and I wait. It can take ten or fifteen minutes before the message appears. I have logged out and back in, with no improvement, rebooted with no improvement, I've run the Nepomuk Cleaner with no improvement. I have installed all available updates, with no improvement. I don't know what else to do.

I really love Kontact and hate the thought of having to migrate back to Thunderbird/Lightning, but I can't live with this glacially slow response time. Any advice would be greatly appreciated.

By the way, I am using KDE 4.11.1 on Kubuntu 13.04 (amd64) with all updates applied.

This fix worked for me:
viewtopic.php?f=154&t=117207&p=290895&hilit=+kontact+akonadi+4.11.1#p290895