Windows 7 Terrible File Sharing (CIFS/SMB) Performance (Windows 7 SP1)

[powerofpi]

Terrible File Sharing Performance on Windows 7 Pro x64 SP1

I am experiencing horrible network share performance with Windows 7 Pro x64 SP1. I have two PCs connected directly with a gigabit ethernet cable and static IP addresses. PC#1 hosts a CIFS/SMB shared folder.

• Yesterday, I was backing up from a CIFS share on PC #1 (running Ubuntu 11.10) to PC #2 (running Windows 7 Pro x64 SP1) at a sustained transfer rate of 80MBps.
• After installing Windows 7 on PC #1 and recreating a CIFS share, I am trying to transfer back the files from PC#2. However, now that both PCs are running Windows 7, I get a transfer rate of 5MBps.
• I have installed all Windows updates and the latest drivers for the network cards on both PCs, yet I still observe a 16x slowdown after I replaced Ubuntu with Windows 7 on PC#1.

Any idea why, or how to fix it? Thank you in advance.