Speeding up Windows Vista web browsing and network performance

This is another in a series of How-To speed up Windows Vista.  If you read my last entry here at Bukisa (called "Speeding up Windows Vista file copying by disabling one feature"), you would have read that Microsoft has put in many "features" to improve performance.  However, for the average user, this had the opposite effect in some cases: slower performance.

The one this article pertains to is the networking and web browsing speed.  You see, there is a feature when browsing networks or receiving information that says the sending computer can only send up to a certain amount of data (a chunk) before it has to stop and wait for the receiving computer to acknowledge it got it. Only then can the sender send the next chunk.    This is called the RWIN (receive window size).

This is limited (on all computers) to be between 2 bytes and 64k bytes (65,536 bytes).  Well, a way to overcome this limitation (which was defined over a decade ago when computers were slower and had less resources is to "scale" it up.  The mechanics are beyond this article, but this is called "TCP window scaling option".  In Windows, this ability was turned off by default in versions of Windows before Vista.  Power Users could play around with settings to get higher speeds.

Vista was the first time it was turned on by default.  It's called Windows Vista TCP auto-tuning. It constantly tries to get higher and faster transmission by playing around with the values used for TCP scaling.  While it sounds good in theory and apparently looked good at Microsoft Labs during Vista development, it turned out to be problematic once Vista hit the real world.  This was primarily due to incompatibilities with the routers installed in users' homes and even some websites.

The solution is to disable this feature. 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=disabled

Now reboot your machine and see if it helps. In most cases, you will notice an improvement in both file copy performance and web browsing.