Comment 43 for bug 1959747

> It seems that the high CPU usage and slow UI update is worse when the message list is big and the window is big. If I make it that only 10 rows are visible, it seems to be faster. Here is a profile of the mouse moving around a large message list.

I can confirm exactly this! Working on a 2 screen setup:

main screen: 3840x2160
secondary: 2560x1440

Arch Linux, Swaywm. Usually all clients (windows) are maximized.

Thunderbird on the main screen has a very bad performance. It is everything else than fun to work with.. :(
As soon as i move thunderbird to the second screen (or switch to floating an make it smaller) the performance increases significantly.

It seems like only the email list is affected. Folder tree for example is fine..

It's been a long time now and kinda renders thunderbird more or less unusable for me. Is there anything I can do to get this fixed? Happy to provide more information if needed!

Thanks for effort :)