samba - Mar 2006 - How to test the fileserver performance with smbtorture (why are my "net use" that slow)?

Hi,
I have some problems here with slow logins. I noticed that the 
login-script runs very slow, i.e. one "net use" takes up to five 
seconds. I updated from samba-3.0.21b to 3.0.21c this Saturday, so I 
don't know if this problem is actually solved. I it possible to test 
that with smbtorture, so I can verify that the fileserver is working 
correctly?
I already tested the network performance with netIO, it was OK (~11MByte/s).
One single user could login very fast - no problem.
Fileserver load is low (load < 1, idle >= 80%).
I gambled a bit with Samba4's smbtorture, but can not find the right 
settings, are there any examples in the web? All i could find describes 
samba3's smbtorture which seems to have a different user interface.
Can anybody give me a hint how to test that?

Thanks,
Malte Mueller