Gregory K. Ruiz-Ade
I've been working to migrate several hundered users on to our new mail servers, which run dovecot 0.99.11 (RHEL4). The problem I'm seeing is that deleting or moving a message seems to take a very long time. It's not uncommon for Thundirbird (1.0.7) to have delays of 5-10 seconds to delete a single message from my Inbox (<500k) and place it in my Trash folder (~100MB right now).
The size of the directory as a whole doesn't matter, the amount of files can cause problems (with certain filesystems).
What's really bugging me is that I've used the same software (RHEL4 and dovecot 0.9x.x) at my last workplace, and the performance was outstanding; it beat UWIMAPd hands-down, especially with large mailboxes. Here, the opposite seems to be true. The primary difference seems to be that we're using NFS here, but I wasn't using NFS at my last job.
NFS can be a real performance killer, but to be sure I'd strace (with -tt) a dovecot process and check where it spends most of it's time.
best regards, Michael Renner