Comment 33 for bug 297143

I get similar 12% CPU utilization from both Xorg and thunderbird/firefox. I'm using Ubuntu 11.04, Thunderbird/3.1.10.
In Thunderbird the problem doesn't happen from the progress bar (which I guess is GTK Theme dependent) but from the rotating 'hourglass' in the top-left corner at the top of the 'Inbox' tab. Not sure either what this waiting signal is supposed to do, at it seems to get stuck waiting randomly on some selected type of messages.