Reopening because the bug still exists and the source is almost definitely the small progress bar at the lower right-hand corner of the Thunderbird window. To narrow it down I would propose for the people having the problem to report their graphics hardware and the cpu usage from top when the problem occurs.
I see: thunderbird ~30-50% Xorg ~20% on an intel GM45 chipset I would also rename the bug to reflect that it's not just when sending mail but also when getting new messages. (in short: whenever the progress bar is active) ** Changed in: thunderbird (Ubuntu) Status: Invalid => Incomplete -- Thunderbird: high CPU while sending email https://bugs.launchpad.net/bugs/109943 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs