"write message" or reply freezes (Mac)

[shweeney]

TB 52.4.0 (64-bit) on MacOS High Sierra

If I click "write message" or reply to a message, the new message box appears but hangs. Might take 20 seconds before I can type in any of the fields and even then it is slow (I don't see the letters until 5 seconds after typing them etc).

I tried "restart in safe mode" and it works fine, so I removed all add ons and restarted, but it still hangs. Creating a new profile also fixes the problem but I'd rather not start from scratch here. AFAIK I haven't made any changes, but I did install Firefox Quantum (which I've now removed as a troubleshooting step).

Any ideas?

[DanRaisch]

Installing or updating Firefox would have absolutely no impact on Thunderbird.

How is the account set up in Thunderbird, as POP or IMAP? Find out using menu path Tools->Account Settings->Server Settings->Server Type at the top right of the dialogue.
Who is the email provider?

[shweeney]

IMAP - it's an internal corporate server. Was working fine up until today, can't think of any changes I've made, other than installing FF. Others in the company are using TB without issue and like I said, works in safe mode, or with a new profile so doesn't seem to be a server issue.

[DanRaisch]

Safe mode does more than disable extensions. Relaunching Thunderbird standard mode, try disabling hardware acceleration using menu path Thunderbird → Preferences->Advanced->General->uncheck "Use hardware acceleration when available."

[shweeney]

Hardware Acceleration wasn't enabled.

Same thing now happening on my laptop (also Mac); this makes me suspect something in IMAP but that wouldn't explain why it works in safe mode. On the laptop it was working one minute (I sent a couple of mails this morning); then I tried to reply to a mail, it hung and now the same thing happens with every mail I try to send. Tried reinstalling the program, no different.

*bangs head off desk*