User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Firefox/104.0

Steps to reproduce:

104.0b3 (64-bit) on Windows 10

Open any folder with a number of messages (it doesn't matter their size) and select all via the menu or using CTRL-A. This will happen whether the account is POP or IMAP.

Even opening a single message takes more time than it should.

Actual results:

If I select 40 simple text messages (i.e., Reddit digest) I can count to 40 until the messages appear in the message window below. The space above the menu bar (title bar?) will flash a "not responding" message until TB comes back again.

This began with 104.0b1 (64-bit) and hasn't gotten any better.

Expected results:

Selected messages should have appeared in the window within a few seconds.

I've 'repaired' the folders. I've deleted the message .sqlite file. I've turned off (and on again) 'Use Hardware Acceleration..". I've restarted in 'safe mode' and flushed the startup cache. I've rebooted the computer in safe mode and ran TB in safe mode. I've chosen to use the default typefaces. I have no addons running.

None of that made a difference.

Worksforme on IMAP 104.0b3 (64-bit), Win10, and 102.1.2 (64-bit), selecting 50+ messages with Shift+PageUp/Down, also Shift+ArrowUp/Down. Multi-preview gets generated pretty much instant in less than a second.

• JmG, does this envolve encryption?
• Any other information about the affected messages?
• How exactly do you select your 40+ messages? (mouse, keyboard etc.)

(In reply to Thomas D. (:thomas8) from comment #1)

Worksforme on IMAP 104.0b3 (64-bit), Win10, and 102.1.2 (64-bit), selecting 50+ messages with Shift+PageUp/Down, also Shift+ArrowUp/Down. Multi-preview gets generated pretty much instant in less than a second.

• JmG, does this envolve encryption?

No it does not.

• Any other information about the affected messages?

Nothing.

• How exactly do you select your 40+ messages? (mouse, keyboard etc.)

Have one message selected and use CTRL-A. Select one message and use Edit/Select/All it doesn't matter. I can easily count out as many seconds as I have messages selected before they'll paint to the screen. Even one message takes more time than it should.

Let me note that this was a sudden change, not something that grew over time.

Pretty sure this is bug 1782725