I've known some people to express frustration over poor torrent performance after upgrading to windows 7, especially people on faster connections. If you've found your torrent speeds lower on windows 7, then this guide is aimed at helping you. This guide will not help with uTorrent or operating-system agnostic settings, I believe that is covered sufficiently in other guides.

I'll mention at the start here that Windows 7 does NOT have a limit on half-open connections, this was removed in Vista SP2. So you don't need the half open connections patch (source: Half-Open Outbound TCP Connections Limit Removed in Windows 7 and Vista SP2 (No Patch Required) » My Digital Life)

Note: this guide is provided 'as-is', the author accepts no liability for outcomes of following the guide here, to the maximum possible extent of the law

1. Disable IPV6

Disabling IPV6 has helped a number of people I know to improve their torrent performance on windows 7. If you need IPV6 on your network, don't disable this. Currently most people don't need IPV6.

Disabling it is easy:
1. go to How to disable certain Internet Protocol version 6 (IPv6) components in Windows Vista, Windows 7 and Windows Server 2008
2. scroll to the 'fix it for me' section
3. select the "Disable IPv6 except for loopback interface" option

2. Disable 'auto tuning'

Windows 7 has some auto tuning functionality which can negatively impact torrent performance.

1. Open command prompt as admin (click start button > type 'cmd' into the search box > right click 'cmd.exe' > click 'run as administrator')
2. to stop windows from automatically undoing your settings, type:
netsh int tcp set heuristics disabled
3. to turn off autotuning:
netsh int tcp set global autotuninglevel=disabled

You can set it back to normal by typing
netsh int tcp set heuristics default
netsh int tcp set global autotuninglevel=normal

3. Compound TCP

Compound TCP is disabled by default, enabling it may improve torrent performance

1. Open command prompt as admin (click start button > type 'cmd' into the search box > right click 'cmd.exe' > click 'run as administrator')
2. type
netsh int tcp set global congestionprovider=ctcp

To restore the default value if you run into problems:
netsh int tcp set global congestionprovider=default

4. Disable QoS

This is a bit of a long shot; you may want to try this if you have something like Skype running all the time on your computer. (QoS reserves up to 20% of bandwidth for high-priority apps if they're running).

1. Click start button
2. Type view network connections into the search box
3. Click on the first result
4. Right click on the appropriate connection (if you use wireless, you should select the wireless connection)
5. Click 'properties'
6. un-check the box next to "QoS Packet Scheduler"
7. Click OK

5. Direct Cache Access

This can improve performance, but only if your hardware supports it.
It is disabled by default. To try it:
1. Open command prompt as admin (click start button > type 'cmd' into the search box > right click 'cmd.exe' > click 'run as administrator')
2. type
netsh int tcp set global dca=enabled

To disable it again, type
netsh int tcp set global dca=disabled

Conclusion

Thats all, I hope some people find this guide useful.