Mail: Minute-long pauses with message area blank, before loading
Problem noticed months ago, slowly getting worse. When opening a new mail message, the message area sometimes appears blank for as long as a full minute before the text loads. This appears to be a pause or stall in the whole app, it still responds to mouse clicks but other messages do not load, either.
Mac Mini late 2014, Monterey 12.6.1, Mail 16.0, active mail connections include two IMAP accounts (Gmail) and one Exchange account (alum.mit.edu).
Just waiting out the delay always seems to work, it's not a permanent freeze.
"Force quit" during the pause always has shown Mail running normally. It had has never said Mail was "not responding." During the pauses, the Activity Monitor has never shown unusual Mail CPU usage.
Rebuilding the mailbox did not help.
Cleaning up the mailbox by deleting large numbers of message or moving them to another folder did not help.
Quitting and re-launching Mail has not helped.
Since the pauses last about a minute, it is hard to tell cause-and-effect. Trying anything sometimes gives the illusion of working but it's just because you've spent a minute doing something.
P.S. Showing two identical Mac mini devices for me and I can't tell which is which, so let me repeat the Mac I am using is Mac mini late 2014 running Monterey 12.6.1