[imp] Speed Issues with IMP and high volume messages

[Eric Rostetter]

Quoting Iain Collins <iain.collins at uk.easynet.net>:

> We use HORDE & IMP here, and have done for quite some time. It's very slow
> opening large mailboxes, that is mail boxes with around 300 or more
> messages, or with several messages with large attachments.

That should not be so.  I *never* have less than 1500 messages in my inbox
and it responds in a fairly timely fashion.

> - For one user with 470 messages (average size is around 2-3K per message,
> there is one 6 MB attachment, and around 4 messages with 2 MB attachments,
> the rest are all typical size), it takes 40 to 50 seconds from clicking
> 'Login' to actually seeing a list of messages (and that was on a test server
> with no other load).

In my setup, with about 16-17K messages, several large attachments, etc.
and it all being filtered at login, it takes about 3-6 seconds depending
on load.  I'd bet a fair amount of the time is the filtering.

> - For another user, with around 3,000 messages (also with an average size of
> around 2K per message), the time between clicking 'Login' and being greeted
> win a message list is 4 minutes). Getting message headers should take just a
> few seconds (and indeed it does, with other IMAP clients).

3000 messages in the inbox is probably excessive, but it surely shouldn't
take that long given sufficient hardware.  You don't mention your hardware...

> The same slowness is oddly also present when clicking 'log off'.

That seems very strange.  I would think maybe this is a problem with sessions
or something, but I don't know how to correlate that with the message number
or size impacting the time.

> Users with smaller mailboxes (e.g. 50-100 message) log on very quickly with
> no issue.

Very strange.

> Finally, the questions:
>
> I'd like to know anyone able to use HORDE with large amounts of messages
> (500-1000) /without/ experiencing similar slowness?

Yes, of course.  That would be the norm.

> Is this just an unavoidable issue caused by the way HORDE handles messages
> (i.e. custom filtering rules/content filtering/etc - even though it doesn't
> matter if the effected customers have filtering on or off, the same slowness
> occurs)?

No.  We have many users with thousands of messages, often hundreds of megabytes
of mail in their inbox, all getting less than 10 second access.

> Can any one suggest a work around for this to improve the speed?

Nope.  No idea what your problem is.  I'd suggest some low level debugging.
Tracing things at the imap server, or on the network via a sniffer, or
something.  Or checking timing within Horde/IMP to see where the slowness
occures exactly.

--
Eric Rostetter
The Department of Physics
The University of Texas at Austin

Why get even? Get odd!