I have a new MacBookPro (model 8,2) with dynamic graphics card switching. When I start thunderbird (without any extensions) - the mac switches to discrete graphics which I think is unnecessary and drains the battery. I found this out by running gfxCardStatus v2.1, and found that thunderbird-bin triggered the discrete graphics.

I see there is a getsatisfaction thread http://getsatisfaction.com/mozilla_messaging/topics/hardware_acceleration_in_thunderbird_5 and there is also a bugzilla ticket https://bugzilla.mozilla.org/show_bug.cgi?id=646043 that seems to be about the same issue, but in core (resolved in nightly). I will try the beta thunderbird to see if the latest versions still have this problem.

Upgraded to 10.0b2 and the issue is resolved. Another happy customer! Thanks very much!