But after upgrading a few machines here and doing some tests, I changed my mind. If Microsoft’s decision to ditch the WGA kill switch in SP1 didn’t convince you, would you be interested in a 300% increase in tripling your network file transfer speeds?

Forget the reports you might have read about SP1 resulting in no performance boost. That story was based on a silly artificial benchmark involving scripting of Office applications. Back here in the real world, where gigabit network connections are now commonplace, you’ll see at least one huge improvement when transferring files over network connections.

In its original release, Vista had some design problems with its networking stack, resulting in slow file transfers, especially when connecting to computers running Windows XP, Windows Server 2003, or Windows Home Server (all three of these products share a great deal of their code base, including core networking components). In Vista SP1, file transfer speeds are dramatically improved. In this post, I’ll describe what I saw.

I did two sets of file-transfer tests using two separate systems configured to dual boot between Vista RTM and the new Vista SP1 release candidate. Both systems have dual- or quad-core processors (both in the Intel Core 2 Duo family) The first group of files consisted of two large DVD images in ISO format, totaling 4.2 GB. The second group of files was a folder filled with more than 3,000 files of all types, in 299 subfolders, totaling roughly 6.5 GB.

For the first test, I transferred the two groups of files from a shared folder on an HP MediaSmart Windows Home Server to the two test systems running Windows Vista RTM, recording the total transfer time for each one. Then I rebooted the two systems into an SP1 installation and repeated the test. I converted the times into throughput rates; here’s the result (note that bigger bars equal higher throughput and thus better performance).

As you can see, the file transfers under Vista SP1 were dramatically faster than the Vista RTM times. For the directory full of many small files, the performance increase throughput was more than 300%; for the large files, the speed increase was roughly 260%. Note that you can expect similar results when transferring files from Vista to systems running Windows XP or Windows Server 2003.

For the second set of tests, I performed transfers between the two machines running equivalent versions of Windows Vista: RTM to RTM, SP1 to SP1. Here, the results were less dramatic. For the folder full of small files, the throughput rate increased by about 50% under SP1, and the large files transferred slightly slower, although still faster than the transfer from Windows Home Server.