sluggish IMAP updating?

[Greg Troxel <gdt@work.lexort.com>]

I use gnus (head of cvs) in emacs 21.4 on NetBSD 3.1ish and 4.0ish, with
my mail in IMAP via dovecot (1.0.0).  I use gnome's mail-notification
and sometimes run thunderbird as well.  Generally this works well.

Typically when new mail arrives I'll notice because of mail-notification
(which is using IMAP's idle extension and thus notices new mail
promptly).  I keep a gnus instance running all day, usually sitting in
the *Group* buffer, and I'll type 'g'.  Usually INBOX will show new
messages, and selecting it will let me reaad them as you'd expect.
Fairly often (perhaps 1 in 4?), typing g will result in INBOX showing 0
messages still.  In these cases, entering the group, exiting it, and
then retyping 'g' will show non-zero messages and I can then enter and
read them.  In these cases thunderbird shows new mail just fine.

I know gnus doesn't push read marks back to the server until the group
is exited, and I wonder if there's some other kind of synchroniziation
issue.  I'll enable imap logging and look at this, but I wanted to ask
if anyone else is seeing this, with dovecot, or with any other IMAP
server.