Microsoft has released software patches for Windows 7-based and Windows Server 2008 R2-based systems powered by AMD's Bulldozer CPUs. These hotfixes are suppose to optimize the performance of Bulldozer CPUs on these systems. The Redmond company did not make these patches publicly available as written requests need to be submitted in order for Microsoft Support to release the appropriate hotfixes.
Microsoft has admitted the performance of AMD Bulldozer CPUs is slower than expected. This is because the threading logic of the operating systems, Windows 7 and Windows Server 2008 R2, is not optimized to use the the Simultaneous Multithreading (SMT) scheduling feature which was introduced in the Bulldozer family of AMD CPUs. According to Microsoft, after the successful application of the patches, these systems with their installed Bulldozer CPUs will operate at the expected performance level.
The support page did not specify any empirical measurements of the performance gains after the successful application of the software patches. In order to apply these patches, the host computer must be running running Windows 7 Service Pack 1 (SP1) or Windows Server 2008 R2 Service Pack 1 (SP1).
Source: Microsoft, AMD