For a while now I've been annoyed when Mozilla Thunderbird hangs while I'm typing an email, during its periodic check for new messages. I'll be merrily typing along (hunt-peck-hunt-pause-peck-backspace), and the composition window will just freeze for upwards of 10 seconds, and come live again when the new message alert pops up to say I have some new messages.
Like I said, I've been annoyed for a while, and today I finally decided to do some digging. Lo and behold, I found this thread from 4 years ago describing exactly this problem.
That thread may have petered out, but the problem is still alive and (?) well. Sadly.
It definitely seems a locking problem and not just the desktop being busy. My client is a fast quad-core, and I can't imagine that an IMAP check and pop-up alert could consume all that ... it seems that a critical resouce must be locked during folder scan or perhaps the related local cache update or update of message counts in the main Thunderbird window.
No doubt the delay is related to how much stuff it has to scan. Admittedly, I have two email accounts configured, to IMAP servers on the same host, and some have some pretty large folders. And that host isn't all that speedy ... But still, it shouldn't block at all.
For the record, I'm using Mozilla/5.0 Gecko/20100429 Thunderbird/3.0.4 under Gentoo x86_64. The thread above mentions this problem in Thunderbird 1.5, so it has been a very long time.
For the record 2: This is still vastly superior to how Outlook handles IMAP.
PS. I tried to first post this as a comment in the other blog, but comments there seem to be busted. So I'll post here and trackback.