In my measurements I did years ago, I found imapproxy to give a small
improvement compared to 0.9x dovecot, I believe that went away in 1.x
versions.
I did use imapproxy on a few systems. But over time I finally gave up
on it, mainly cause it kept crashing, causing webmail to stop working,
and I didn't feel adding a watcher or looping it to keep it running to
be the correct fix. And given the very small improvment it gave, felt
it wasn't worth the hassle of dealing with.
Quoting Timo Sirainen <tss@iki.fi>:
On 25.6.2010, at 1.37, Noel Butler wrote:
If its running on a SOHO, you probably wouldn't even be able to measure the difference, but for an ISP/Telco or large institution, you will certainly notice the reduction in I/O (or loads on your database server). This goes for any imap webmail software, not just SM.
But with auth cache enabled, there is no extra database load. The
index files are also most likely in OS's cache (assuming local
disk), so no extra disk I/O to read them either. I'm sure it's a bit
more extra CPU usage, but I'm not all that certain that it's really
that a big of a difference with Dovecot.