Microsoft KB article 929868 describes a problem which will cause you to experience very slow browsing on certain websites when using IE7 on Windows Vista, and eventually the website might even drop the data completely.
To work around this issue you might consider changing the Windows Scaling factor to 2. To change the Windows Scaling factor to 2, follow these steps:
1 - Click Start and type CMD.
2 - Press CTRL+SHIFT+ENTER to open the command Prompt with Administrative rights.
3 - At the prompt in the Administrator: Command Prompt window, type the following command, and then press ENTER:
netsh interface tcp set global autotuninglevel=highlyrestricted
This will set the autotuninglevel to "Allow the receive window to grow beyond its default value, but do so very conservatively".
To read more about the netsh command in Windows Vista please use Vista's help and support tool. You will need to reboot in order for the setting to take effect.
You can easily restore the setting back to the default by typing
netsh interface tcp set global autotuninglevel=normal
Remember to reboot in order for the setting to take effect.
You can also disable autotuning with the following command:
netsh int tcp set global autotuninglevel=disable
Again, you will need to reboot in order for the setting to take effect.
It seems that disabling the autotuning feature will speed up threaded network downloads, mostly used with all sorts of downloading agents and per-to-peer networking, along with great improvement with file copying on your network.