|Ran into some issues updating to courier-imap-4.0.6-r3 on my VPS so I
|decided to take the plunge and go straight to 4.5.0 which is unstable.
|4.5.0 is much faster and Thunderbird barely registers email in the Inbox
|before the messages are moved to the appropriate folder. My installation
|is also a combination of cyrus-sasl, authdaemon from courier-authlib,
|Mysql based virtual accounts, ssl certs for imap and smtp, and Postfix.
|No changes were needed in courier-imap config files other than restoring
| I don't think Courier-imap is faster than Dovecot based on other
|people's experience, but has rather reached speed parity with it. If
|you're already on Dovecot and happy, stay, if you've been thinking about
|Dovecot but have a complex system to move I'd recommend trying the
|upgrade to 4.5.0.
| I also update gamin and use +fam with courier-imap which might affect
|the overall speed. The update from 0.1.9 to 0.1.10 doesn't look like it
|would account for the increased speed.