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)
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)