cifs mounting issues

[sc0ri0n]

I hit my first problem since I upgraded to FC4: I had  mount points that
connected to different XP drives using something like

mount -t cifs -o
username={username},password={password] //{machine_name}/{share} /mnt/c

There does not seem to be a problem during mounting but then when I try
to access the mount point, what used to be an instant thing takes ages
now. 

If I replace cifs with smbfs, everything is back to up to speed.

Is anyone else having such problems?  Any leads how to troubleshoot
this?

Thanks,
Adil