Mousing oddities in v91.1.0

TB 91.1.0
opensuse tumbleweed
linux 5.14.2-1-default x86_64

Since the update to v91, actions involving the mouse have changed.

  1. When the mouse is moving over folders in the account/folder pane, the hover
    highlight is delayed by roughly a half a second. This gives the impression of a
    very slow processor struggling to catch up to the mouse’s position.

  2. A similar effect occurs for the message tree/list pane. The delay is less in

  3. In the message pane, the mouse wheel is ignored until I either click on that
    window, or move the mouse to hover over actual content rather than over empty space.

None of these behaviors were present in the earlier version before v90. (I
believe it was 78.x esr; it may have been a more recent version.)

Is this the new normal?

Maybe your Thunderbird is indexing / downloading messages.

I don’t know why but somehow my Thunderbird (Beta) decided to re-download all of my 20000 or so emails which took several hours and during this time the whole interface was greatly slowed down.
You can see if your Thunderbird is synchronizing when you double-click the bottom-left status bar.

Screenshot 2021-09-25 10.18.38

None of the accounts store the mail locally; it is all kept on the server. The lagging hover response occurs at any time.