A Knowledge Base (KB) article and related software update was released on the May 20th 2008 that seems to have gone fairly unnoticed by quite a few people. The article (http://support.microsoft.com/kb/952830) is rather vaguely titled "Description of Windows Script 5.7 for Windows XP" and it details the updated version of the Windows Scripting Host for Windows XP, along with a brief summary of the files that it contains. The reason I think that it has gone fairly unnoticed is because all the useful information for this update is contained in the release notes (which you have to download manually and extract from the compressed file) rather than on the KB page where it should be. This makes it pretty unlikely that anyone will know what changes have been made and what improvements the update offers.
The update contains a lot of fixes but there is one fix in particular that is probably going to be useful to many people. It is the following:
Fixed attempting to load nonexistent wshenu.dll which created performance problem in login scripts
What this means is that, if you have a logon script that has been developed in Visual Basic Script (VBS) that seems to execute slower than it should, then by applying this update you could gain performance benefits during the scripts execution. Quite often I have seen VBS logon scripts that seem to take too long to execute with no obvious reason why, well this may be the reason!
Of course, it could be that the reason your script runs slow is because of programming errors or other factors not related to the scripting host, but if you are sure that your script is designed well and contains no errors then perhaps this update can solve your performance problems.
Thanks to a buddy of mine, Mauricio Tamayo, for pointing this out to me!