The Tech-Report has taken a closer investigative look at the Windows XP kernel update we revealed on Sunday June 15th. The story has caught fire on Monday June 16th, after the MS knowledge base article was altered and the hotfix became downloadable. Unfortunately the Tech-Report's benchmarks show that fixing something is not always beneficial: In our testing, enabling Hyper-Threading on a Pentium 4 processor has generally resulted in lower performance in Content Creation Winstone tests. I wondered if this performance hit might be associated with Windows XP's mishandling of the UnmapViewOfFile function, so I ran some tests. Unfortunately, the results aren't encouraging. Microsoft's Q815227 hot fix for Windows XP doesn't improve Hyper-Threading performance in the Content Creation Winstones, and it actually slows Hyper-Threading performance in the Business Winstone tests.