[Samba] DFS slow -- UNC fast -- why would this be ?

[Greg]

butter fingers,  sorry....

Hello,
   A week has passed and we are still spinning our wheels trying to work 
this out..  If anyone has a recommendation as to what I should try I'd 
love to hear it,  thanks. 
Our PDC is running older code of the TNG w/LDAP branch (0.3.2).
The DFS service is running on another machine,  have tried both samba 
2.2.3 and 3.0.8/9.  Results do not change using either version.  We have 
even moved it to more robust hardware and placed it on a gigabit segment.
The file servers are running mostly 3.0.x,  while some are 2.2.3. There 
is about 150 client machines on the network.

The problem:  Using UNC paths,  we see threwput as expected,  the test 
file takes 1-2 seconds to write.  going threw the N: drive (which maps 
to the DFS root on the DFS server)  times go up to and beyond 60 
seconds.  This is not consistent.  sometimes it will write to N: drive 
mounted shares as fast as UNC,  but most of the time not.   Using the 
UNC path always performs in a consistent, fast manner. 
What might I do to trouble shoot this?  Thanks for your help.

greg