If you run any P2P or torrent software with Windows XP SP2 you may run in to some network performance issues. This is due to Microsoft reducing the number of half-open concurrent connections from 65,000 to 10 as part of SP2.
When the limit of 10 is reached any further connections are queued up and released by Windows at a rate of 10 per second.
This limit was introduced to reduce the speed at which viruses and worms etc using PC's can spread themselves. However the side effect means some networking applications struggle to function as intended.
Checking the Windows System Event Log will show a warning for Event ID 4226:
A patcher exists at www.lvllord.de
Download and run the file EvID4226Patch.exe
It will detect the version of TCPIP.SYS and tell you the current limit for concurrent half-open connections.
Pressing Y to install the patch will change the limit to 50.
You also have the option to change the limit to any value between 10 and 16777214.
After a restart the new limit will take effect.
EventID 4226 Patcher from LvlLord