Really slow IMAP performance

[Neil Jerram]

Aki Tuomi <aki.tuomi at dovecot.fi> writes:

>> On 24 February 2018 at 15:47 Neil Jerram <neil at ossau.homelinux.net> wrote:

[...]
>> >  Feb 24 10:24:24 arudy dovecot[1712]: imap(neil): Warning:
>> > Transaction log file
>> > /home/neil/dovecot-mail/.imap/INBOX/dovecot.index.log was locked
>> > for 98 seconds (Mailbox was synchronized)
[...]

> You are using mbox format. This is ... bit slow. =)
>
> When you move mails between mbox files, it has to rewrite the entire mbox file every time. You should probably start using maildir or sdbox instead.

Ah, right, thanks.

My INBOX file has 22990 messages.  Is the slowness that I am seeing
definitely expected for an mbox of that size?  (It may also be relevant
that the HDD it's stored on is pretty old now, and has been known to
report SMART errors...)

If so, I'll start looking at how to migrate, given that my system is
Postfix + Dovecot.  If you have any particular recommendations or
migration pointers for a system like that, I'd appreciate them.

Best wishes - Neil