Nagle’s document, Congestion Control in IP/TCP Internetworksdescribes what he called the ‘small packet problem’, where an application repeatedly emits data in small chunks, frequently only 1 byte in size. Since TCP packets have a 40 byte header (20 bytes for TCP, 20 bytes for IPv4), this results in a 41 byte packet for 1 byte of useful information, a huge overhead. This situation often occurs in Telnet sessions, where most keypresses generate a single byte of data which is transmitted immediately. Worse, over slow links, many such packets can be in transit at the same time, potentially leading to congestion collapse.
Procedure to follow
1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\Software\…[the rest of the path goes to where the client app for your game is]
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type TcpNoDelay for the name of the DWORD, and then press ENTER.
5. Right-click TcpNoDelay, and then click Modify.
6. In the Value data box, type 1 to turn on the Nagle algorithm socket option, or type 0 to turn off the option.
7. Click OK, and then quit Registry Editor.
For world of warcraft registry key as follows
HKEY_LOCAL_MACHINE\Software\Blizzard Entertainment\World of Warcraft\TcpNoDelay
Data 0c00000000 (0)