Gnus hangs after "Quickly checking mailbox INBOX" for way too long

[Sébastien Vauban]

Hello,

I want to come back on this old thread launched by someone else:

    ,----[ nnimap slow on checking huge mailboxes? ]
    | Newsgroups: gmane.emacs.gnus.general24
    | Date: 2006-06-29 19:56:32 GMT (2 years, 33 weeks, 4 days,
    | 3 hours and 26 minutes ago)
    |
    | Hi,
    |
    | When I hit 'g' nnimap takes a long time to check for new
    | messages in big mailboxes (i.e. 11000 messages).
    | Is there a way to make this faster ?
    |
    | when I do 'g' emacs does :
    |      Quickly checking mailbox ...
    | and scans rapidly the mailboxes.
    | after that it does :
    |       Mailbox: ..... modified
    |
    | and scans slowly (taking >1 minute for big boxes!) the mailboxes
    |
    | I'm using emacs/gnus from cvs and checked that I have the latest
    | nnimap.el
    | The IMAP server runs locally and is Courier.
    |
    | any idea ?
    `----

... still having the same problem with No Gnus v0.9 under GNU
Emacs 23.0.60.1 (in Ubuntu 8.04) with the email server being
Courier, located on a 1 Gbps LAN connection.

Checking for new mails takes a very, very long time, to the
contrary of what's being said ("Quickly checking...").

I must admit I keep every mail I receive, for the 5 years I'm
using Gnus. That is around 90,000 mails spread over 40 groups or
so -- the main one, for the work, containing 20,000 emails.

Is there a way to make this happen fast, or at least faster?

Best regards,
  Seb

PS- The colleague I've managed to attract to Gnus experience the
    same problem (with much less emails) on GNU Emacs 22 on
    Windows.

-- 
Sébastien Vauban