In both my Inbox and my saved email folders, when I click on an end-to-end encrypted email, Thunderbird (v145) displays "Loading Message..." and then blocks with a spinning blue "working" cursor for on the order of 30-60 seconds. The Thunderbird dialog then appears to make some progress, as the windows seems to "flash" as if it's being cleared, but the email content doesn't appear. After about another 20-30 seconds, the encrypted email contents appear, correctly decrypted.

This long delay only occurs when I click on encrypted email messages, and it happens every time I click on an encrypted email message, and this behavior only started occurring in the past couple of days (correlated, I believe with Thunderbird updating to v145) so I think it's safe to assume the issue is with end-to-end encryption/decryption in Thunderbird v145.