Speed-up fix for large file copy in Vista

April 24th, 2007

A couple of readers e-mailed me to point out this possible fix that helps to speed-up large file copy under Vista.

Here's the problem:

Maybe you have already encountered the strange behavior that it takes much longer to copy large files in Windows Vista than in Windows XP. You thought that the change from XP to Vista would at least be not a disadvantage speed wise but Vista somehow seems to have a problem copying large files. This happens especially with mapped drives but it could also be that you witness network disconnects.

Here's the cause:

The problem is caused by a new feature called Auto Tuning which is by default enabled in Microsoft Windows Vista. What Auto Tuning does is that it reacts on changes in the network by tuning the receive windows size. The solution would be of course to disable Auto Tuning in Vista. Some users reported that disabling Auto Tuning had a positive effect on their ability to connect to services such as Windows Live Messenger which did not work before.

Here's a fix:

To disable Auto Tuning and speed up the copy process and avoid timeouts and disconnects do the following:

Open a command prompt and type the following:
netsh int tcp set global autotuninglevel=disabled

To turn it on again:
netsh int tcp set global autotuninglevel=normal

I've tried this and it seems to help matters and doesn't seem to have any nasty side-effects (that I can see) but I think we need to wait for a patch (or maybe even SP1) before we get a proper fix for this problem.

This entry was posted on Tuesday, April 24th, 2007 at 12:53 and is filed under PC Doctor Tips, PC Doctor's Useful Links. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

One Response to “Speed-up fix for large file copy in Vista”

  1. Windows Vista - Windows Live Messenger error 81000306 Says:

    [...] interesting fix, must make some time to look that one up. There’s more about autotuninglevel here. Stephen Lamb has produced some good information over here (originally via [...]