[imp] up-imapproxy and select caching

[Aria Bamdad]

Hi,

I have an installation of Horde Groupware webmail Edition 1.2.2, with
IMP 4.3.3 and PHP 5.2.5.

The Horde Performance Guide

http://www.horde.org/horde/docs/?f=PERFORMANCE.html

under IMAP tuning says that if using up-imapproxy, "make sure SELECT
caching is turned off".

When I do this, I get poor performance because the up-imapproxy unselects
the mailbox after every single transaction, so the entire mailbox index
structure for a given mailbox has to be reloaded for every single
transaction.  This is something that the developer of up-imapproxy
is aware of.

When I turn on select caching, IMP performance is excellent.  My question
is why does the above Horde document say to turn off the select caching?
Does turning on select caching cause a problem?

Thanks.