samba - Aug 2006 - Slow Samba performance with single transfers (good speed with mulitple transfers)

System:
Gentoo Linux, fully updated (8/19/2006), Kernel 2.6.17.9 stock kernel,
samba-3.0.22-r3 (have also tried samba-3.0.23b), 1Gb Ethernet. (thoughout).

Problem:
Very poor performance when copying files to or from the client, (ie 2000kb
or lower on writes, 5000kb or lower on reads).

Detailed Problem:
If I use SCP from the same source to the same target (including drives), the
speed of the transfer is over 10000kb), now if I try a samba transfer at the
same time as the SCP then the total speed is 42000kb or 11000kb for scp and
31000kb from samba), same thing if I try copying from the samba server and
copying to the samba server at the same time then the speed is 24000kb up
and 18000kb down, if I stop one or the other the speed drops to 2000kb or
so.  Now I'm at a complete loss as to what is causing this speed issue and
I've tried diffrent kernels and versions of samba as well as modifying the
smb.conf file, but nothing seems to change the result.  I thought it might
be the harddrive, but that would not explain the lone SCP issue I'm
encountering.

Looking for a solution, which does not include switching to windows or
reinstalling the OS.

Samba Config File:
workgroup = 51west
netbios name = 2.0TB RAID5
server string = FileServer
encrypt passwords = yes
hosts allow = 192.168.0. 127.
domain master = no
local master = no
preferred master = no
os level = 0
security = share

[Private]
path=/raid5/private
comment = Private Folders
browseable = yes
readonly = no
valid users = egandt


Thanks,
ERIC GANDT