On Sun, 2010-02-07 at 13:40 +0100, Stefan Foerster wrote:

For 100k messages, delivery to a Maildir store using Postifx's pipe(8) and Dovecot's deliver took 4319s, which equals 23.15 delivieries per second - and that's with the pipe(8) delivery agent haning around for up to 100 seconds, being reused for multiple transactions.

Dovecot 2.0, with LMTP, was finished after 4007s, which equals 24.96 deliveries per second.

You could also try if maildir_very_dirty_syncs=yes affects it.