samba - Jul 2013 - Incredible slow logon on Samba4 domain

Hi everyone, I am facing a major trouble with my Samba4 domain

Just installed Samba 4.0.6 on Centos 6.4, using internal DNS, when I add an
W7 client it is a little bit slow to join the domain, but when I login as
as Samba user it takes over 15 minutes. is there any trick to get it faster?

I am using an internal DNS server, but it hapens the same with Google or
OpenDNS.
My resolv.conf is pointing to the samba4 server.

My smb.conf
------------------
# Global parameters
[global]
        workgroup = VALE
        realm = VALE.LOCAL
        netbios name = SAMBA4
        server role = active directory domain controller
        allow dns updates = nonsecure
        dns forwarder = 172.16.18.13

[netlogon]
        path = /opt/samba/var/locks/sysvol/vale.local/scripts
        read only = No

[sysvol]
        path = /opt/samba/var/locks/sysvol
        read only = No
----------------------------

Patrick