[Dovecot] Optimizing POP3 performance?

[Sebastian Färber]

Hello,

I recently migrated to Dovecot from Courier-IMAP and i'm very happy
with the IMAP Performance and Dovecot in general.
The server is running qmail-ldap and i'm still using the qmail pop3
daemon for the POP3 users.
Because i want to get rid of qmail completely (switching to exim) i
just tried to replace the qmail pop3 daemon with dovecot too.
Immediately after the migration the server became basically unusable
because of the high I/O Load caused by the dovecot pop3 daemon.
I did some debugging and it looks like dovecot opens every old mail in
a users maildir and wants to create it's index files etc.
I tried running dovecot pop3 with and without "in memory" indexes but
this didn't change anything. Is it possible to disable the indexing
of the old e-mails completly for pop3?

I understand that dovecot is primarily an IMAP Server but i didn't
expect the POP3 Performance to be that bad compared to the qmail
pop3 daemon (which is very very basic i have to admit). Is there
anything i may have overlooked which helps with the POP3 Performance,
any
patches that disable the unnecessary indexing etc.?
If not, what do you guys recommend and use as a pop3 daemon that is
fast and stable?

I'm using dovecot 1.0.2 (i checked the ChangeLog, doesn't look like
upgrading would give better pop3 performance?) and the relevant
pop3-config
is:
mail_location: maildir:~/Maildir:INDEX=MEMORY
mail_debug: yes
dotlock_use_excl: yes
maildir_copy_with_hardlinks: yes
mail_executable: /usr/local/dovecot/libexec/dovecot/pop3
mail_plugin_dir: /usr/local/dovecot/lib/dovecot/pop3
pop3_enable_last: yes
pop3_uidl_format: %f
pop3_client_workarounds: outlook-no-nuls oe-ns-eoh

Any hint in the right direction is greatly appreciated

Regards,

Sebastian Faerber