[imp] IMP speed

[Simon Matthews]

I did a few more experiments to compare IMP's performance with POP and IMAP 
servers.

I compared the speed of IMP with an IMAP server to IMP with a POP server.

Once the initial list of email addresses is loaded, IMP with an IMAP server 
is MUCH faster. The time to open an email is shortened dramatically.

Also, the load on the machine that hosts the POP/IMAP server is much less 
with IMAP. Using 'top', whenever I opened a single email on the IMP/POP 
setup, I could see ipop3d taking a significant proportion of cpu time. 
Using IMP/IMAP, the imapd did not show up in top after the initial loading 
of the inbox.

It looks like the installation instructions should strongly suggest people 
use IMAP!

Simon