samba - May 2005 - Strangely slow tranfers speeds with samba 3.0.10 and FC3...

Ok, I've found some references to this issue with samba on the net, but not
related to the version of samba I'm running (which is 3.0.10, updated
version that comes with Fedora Core 3).

My problem is this, I've got a Compaq Proliant 2500 (dual Pentium Pro-200MHz
with 256MB RAM and the standard Netintelligent 10/100 network controller
that come with it)... I've narrowed down that hardware isn't a problem
because I can get a comfortable 9 MB/s transfer rate from this machine using
FTP.

My problem is Samba, more specifically reading a file from a samba share. I
can read a 350 MB file at a horrendously slow speed of 0.85MB/s, it takes
more than 10 minutes for the file to be transferred, when I use a Windows XP
or Windows 2000. If I use Windows 98 it takes just over 2 minutes.

Now, the strange thing is that if I log into my samba server, mount a volume
from my Windows (2k/XP) PC with smbmount and copy the file to the mount
point, it takes just over 2 minutes. If I write to the samba server (copy a
files from the windows (98/2k/XP) PC to the samba server) it takes just over
2 minutes. In these situations the transfer rate is about 5MB/s.

So the problem is specifically Windows 2000 or XP reading from the Samba
server. I've seen a reference to a problem similar to this but the person
was using samba 2.2, incidentally I have an old Samba 2.2 (RH7.2) on the
network (which I was hoping to replace) that does not suffer this problem, I
can't compare the rates as the hardware is much inferior (a Pentium-133MHz
with 32MB RAM) but the read and write speeds are similar and it takes just
over 3 minutes to read a 350MB file with Windows 2k/XP clients, so it's a
lot faster than the Proliant 2500!

I've tried disabling oplocks, switching NetBIOS off (using just TCP/IP),
doubling the send and receive buffers, etc... all to no avail!

Any help would be most appreciated.

Thanks in advance,

Peter.

PS: The detail of my setup (anything else you need please ask)...

Dist: Fedora Core 3
Kernel: 2.6.11
Samba: 3.0.10-1.fc3 (latest Fedora Security Release)

Output of testparm:

Load smb config files from /etc/samba/smb.conf
Processing section "[printers]"
Processing section "[shared]"
Loaded services file OK.
Server role: ROLE_STANDALONE
Press enter to see a dump of your service definitions

# Global parameters
[global]
        workgroup = REDE-CASA
        server string = Novo servidor Proliant 2500 - PPro Dual
        interfaces = 192.168.1.6/24, 127.0.0.1/8
        bind interfaces only = Yes
        security = SHARE
        log file = /var/log/samba/%m.log
        max log size = 50
        socket options = TCP_NODELAY SO_RCVBUF=16384 SO_SNDBUF=16384
        printcap name = /etc/printcap
        local master = No
        dns proxy = No
        wins support = Yes
        idmap uid = 16777216-33554431
        idmap gid = 16777216-33554431
        hosts allow = 192.168.1., 127.
        cups options = raw

[printers]
        comment = All Printers
        path = /var/spool/samba
        printable = Yes
        browseable = No

[shared]
        comment = Shared file space
        path = /smb/shared
        read only = No
        guest ok = Yes