(In reply to Frank from Matrix and #68) > I narrowed it down to a change between Thunderbird 110_0b4 and 111_0b1.
That's good work. Bad news: the number of [Firefox](https://hg.mozilla.org/releases/mozilla- beta/pushloghtml?fromchange=FIREFOX_110_0b4_RELEASE&tochange=FIREFOX_111_0b1_RELEASE) and [Thunderbird](https://hg.mozilla.org/releases/comm- beta/pushloghtml?fromchange=THUNDERBIRD_110_0b4_RELEASE&tochange=THUNDERBIRD_111_0b1_RELEASE) patches in that span is massive. Good news: 111.0b1 is the first beta with Supernova code. So there is a high chance the cause is Supernova code whose first daily build is 2023-01-16. Bad news: I'm guessing the cause is straight up Supernova "ash" massive code landing on 2023-01-17. So you might try **nightly** builds on either side of 2023-01-17. If the problem is not seen there, use mozregression to try **nightly** builds between and 2023-02-27 (above comment edited to remove duplicate text) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to thunderbird in Ubuntu. https://bugs.launchpad.net/bugs/1959747 Title: [upstream] Very high CPU and slow responsiveness in Thunderbird 91-102 Status in Mozilla Thunderbird: Confirmed Status in thunderbird package in Ubuntu: Triaged Bug description: Very high CPU and slow responsiveness in Thunderbird 91.5.0 and later. Just moving the mouse cursor over a message list results in 365% CPU for me. I had to set this in the config editor to fix it: gfx.webrender.force-disabled = TRUE Upstream bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1730423 To manage notifications about this bug go to: https://bugs.launchpad.net/thunderbird/+bug/1959747/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp