Microsoft released on Friday a newer version of the SP1 Release Candidate for Vista.
The newer version, dubbed "Refresh", requires uninstalling the earlier version of the SP, and installing 2 additional hotfixes.
I haven't tested it yet, but I hope it improves performance further. You can download Refresh here.
Usually, Microsoft does not release RC versions to the general public, and definitely not incremental improvements, but, as been noted before, they are with their backs to the wall with Vista.
On the same subject, read this funny post, of a user who upgraded FROM Vista (guess to which OS? ).
Just installed the Refresh version. The download contains is a cmd batch file and 2 documents. The batch adds 2 keys to your registry that will allow your Windows Update to see the new patch.
Installation is a major hassle: at least an hour to uninstall the existing SP1 version, one hour that the documentation asks you to wait between uninstalling the old version and installing the new one, and one more hour to install the new version. And I didn't even count the number of restarts (more than 5, closer to 10).
I'm not looking forward to installing the final release version - apparently the installation process will be the same.
I still can't notice any improvements over the previous version. My Windows version now shows 6.0.6001.744.