[Dovecot] speed up dovecot IMAP server

Hello,

I upgraded my dovecot server (1.2 -> 2.1), from debian backport because it was a little slow (wait 5-6 sec) when I opened some mail (but not every mail). Unfortunately, the mail open speed didn't increase. I think it's an index problem. Have you idea for fixing?

My conf:

http://pastebin.com/FNLusi51 [1]

(HP Microserver with 6 Gbyte RAM - entry level server with small load and small (max. 40) concurrent connection)

Best regards, Gabor

Links:

[1] http://pastebin.com/FNLusi51