The fix which only requires you to change 2 small things in the windows registry allows your ping in World of Warcraft to drop by 100-150, and it only takes about 5 minutes to apply.
Warning:
If you aren't comfortable changing files in your registry you may just want to wait for blizzard to create a working fix.
1 - TcpAckFrequency:
NOTE; if you are running Windows Vista this setting may not have any effect - a hotfix is needed which i'm tracking down. This works fine under Windows XP
Type "regedit" in windows "run.." dialog to bring up registry menu
Then find:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic
es\Tcpip\Parameters\Interfaces\
There will be multiple NIC interfaces listed in there, find the one you use to connect to the internet, there will be several interfaces listed (they have long names like {7DBA6DCA-FFE8-4002-A28F-4D2B57AE8383}. Click each one, the right one will have lots of settings in it and you will see your machines IP address listed there somewhere. Right-click in the right hand pane and add a new DWORD value, name it TcpAckFrequency, then right click the entry and click Modify and assign a value of 1.
You can change it back to 2 (default) at a later stage if it affects your other TCP application performance. it tells windows how many TCP packets to wait before sending ACK. if the value is 1, windows will send ACK every time it receives a TCP package.
2 - TCPNoDelay:
Type "regedit" in windows "run.." dialog to bring up registry menu
Then find:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Paramet
ers
Right-click in the right hand pane and add a new DWORD value, name it TCPNoDelay, then right click the entry and click Modify and assign a value of 1.
Click Ok and close the registry editor, then reboot your PC."
Basically, this fix is deactivating the Nagle algorithm to improve your ping. If you don't want to do it you can just wait for the 2.3.2 patch as it's supposed to deactivate it too, but I don't think you can test it on PTRs right now because the updated patch notes from the latest PTR Build (7705) are actually for the upcoming build (7710).
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