Unexplained slow gigabit network speeds

Solution 1:

Try disabling Window's auto-tuning feature.

In a CMD window:

netsh interface tcp set global autotuning=disabled 

Re-run your test, and see if you notice a performance improvement. I've had to do this on a couple of laptops running Windows 7 in my house, and it's helped.

If things get worse, or you don't notice any improvement, you can re-enable autotuning by:

netsh interface tcp set global autotuning=normal

Solution 2:

This seems to be a big issue with Windows 7. Several gamers have complained about this issue.

1. From a command prompt (usually in All Programs -> Accessories -> Command Prompt) run “regedit”
2. Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameters\Interfaces
3. Browse the items under interfaces until you find one that has an IPAddress entry matching the network interface you want to affect (typically LAN IP addresses start with 192.168 or 10.0); note that if your IP address is automatically assigned by a DHCP server you may need to look for a matching DhcpIPAddress instead of IPAddress
4. Right-click on the interface and select New > DWORD (32-bit) Value, name it “TcpAckFrequency”
5. Right-click the new TcpAckFrequency value and select Modify, enter “1″ (Hexadecimal radio button should be selected)
6. Right-click on the interface and select New > DWORD (32-bit) Value, name it “TCPNoDelay” (note that TCP is all uppercase this time – that’s intentional)
7. Right-click the new TCPNoDelay value and select Modify, enter “1″ (Hexadecimal radio button should be selected)
8. Verify that both TcpAckFrequency and TCPNoDelay now show up in the adapter’s property list with types REG_DWORD and values 0×00000001
9. Exit regedit and reboot (reboot is necessary for the changes to take effect!)
   10. Play a game and enjoy your new low ping

This decreased my ping in most games from 200-300ms to 50-60ms, which matches the latency I would see via a tracert to the game’s server.

Taken from reduce game network latency in windows 7 or vista

Solution 3:

To verify whether the laptop is not at fault, run up an ubuntu live cd, install iperf onto the ramdisk and run a test.

This should at least test the network side of it.

Solution 4:

Check for dropped packets. Not sure how to do this in windows, but if you have a linux machine you can check there.

I had a similar experience with a gigabit switch where the gigabit mode was broken and dropping packets. I only saw trouble when I had 2 machines connected in this mode. In 100K mode, everything was fine. It was a nasty problem which took me a few days to find out. I might have been a D-Link. Do some googling about your model of switch. I did and found others had the same problem as me.