[Dovecot] GSSAPI makes webmail access really slow

[Nicolas GRENECHE]

Hello,

I use dovecot 1.2.15 as an IMAP backend for Horde webmail.

When I enable PLAIN and GSSAPI as authentication mecanisms, it makes
Horde very slow.

If I enable only PLAIN it is a lot more fast.

Do you have a clue to solve this issue ? Here is my dovecot.conf :

protocols = imap imaps pop3s managesieve

mail_location = maildir:/ext/spool/imap/%1Mu/%u

first_valid_uid=97
last_valid_uid=97

ssl_cert_file = /usr/local/cert/mailper/cert.pem
ssl_key_file = /usr/local/cert/mailper/mail.key
ssl_ca_file = /usr/local/cert/mailper/chain.pem

auth_debug = yes
disable_plaintext_auth = no

## tuning ##
login_process_size = 64
login_max_processes_count = 196
login_max_connections = 384
auth_worker_max_count = 30
## fin tuning ##

protocol imap {
        mail_plugins = quota imap_quota
        ## tuning ##
        login_processes_count = 4
        ## fin tunning ##
}

protocol pop3 {
        mail_plugins = quota
        ## tuning ##
        login_processes_count = 3
        ## fin tunning ##
}
auth_cache_size = 4096
auth_cache_ttl = 1800

protocol lda {
        mail_plugins = quota sieve
        postmaster_address = root at example.fr
}
protocol managesieve {
        listen = *:2000
}

mail_uid = vmail
mail_gid = vmail

auth_krb5_keytab = /etc/dovecot/keytab/pop-imap.mail.keytab

auth default {
  socket listen {
        master {
           path = /var/run/dovecot/auth-master
           mode = 0600
           user = vmail
        }
  }
  mechanisms = plain
  passdb pam {
        args = max_requests=50 cache_key=%u%r dovecot
  }
  userdb static {
        args = uid=vmail gid=vmail allow_all_users=yes
  }
  user = root
}

dict {
}

plugin {
        quota = maildir:User quota
        quota_rule = *:storage=1G

        # The location of the user's active script:
        sieve_dir = /ext/spool/sieve/%1Mu/%u
        sieve = /ext/spool/sieve/%1Mu/%u/dovecot.sieve
}