[imp] Speed Issues with IMP and high volume messages

[Iain Collins]

Hi,

First, some background information:

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.

300 may be considered a lot, but is not - IMO - /excessively/ large. Some of
our users have 1000's of messages in their mail box and other solutions cope
admirably.

We have a cluster of IMAP servers (to go with the cluster of HORDE webmail
servers, which are running FreeBSD) on a local LAN, and using other methods
to login and retrieve mail (together with putting some time stamps in
HORDE/IMP) have shown it's definitely HORDE/IMP and it's poor handling of
these large mailboxes which is to blame. None of the servers in question are
under heavy load.

As examples of the scale of the delay:

- 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).

- 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).

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

Were not using the version latest version on the live cluster (because we'd
need to rebrand it and customise it again), but I've tried the latest
version on a test server and it's not any better, I've also tried using PHP
Accelerator , but it doesn't seem to have helped either (it's a message
handling issue, rather than a PHP being slow issue it seems).

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

Finally, the questions:

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

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)?

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

Your assistance and insight is greatly appreciated in advance.

Best regards,

-- 
Iain Collins, Systems Developer
Email: iain.collins at uk.easynet.net
Mobile: +44 (0) 7876 506 242