This patch has been pulled by Microsoft as some users have complained that it actually further lowers performance. See this story.
Microsoft today released a hotfix for Windows 7 users using AMD’s ‘Bulldozer’ chips that aims to address performance issues with simultaneous multithreading.
According to the hotfix page: This article introduces an update that optimizes the performance of AMD Bulldozer CPUs that are used by Windows 7-based or Windows Server 2008 R2-based computers. Currently, the performance of AMD Bulldozer CPUs is slower than expected. This behavior occurs because the threading logic in Windows 7 and in Windows Server 2008 R2 is not optimized to use the Simultaneous Multithreading (SMT) scheduling feature. This feature was introduced in the Bulldozer family of AMD CPUs.