Performance impact of Spectre and Meltdown patching on Windows Systems

Terry Myerson wrote in a blog post the summary of what Microsoft has found so far. With Windows 8 and Windows 7 on older silicon (2015-era PCs with Haswell or older CPU) they expect most users to notice a decrease in system performance. That’s because older versions of Windows have more user-kernel transitions, such as font rendering taking place in the kernel.

With Windows 10 on older silicon (2015-era PCs with Haswell or older CPU), some benchmarks show “more significant slowdowns”, but with Windows 10 on newer silicon (2016-era PCs with Skylake, Kabylake or newer CPU) Microsoft doesn’t expect most users to notice a change because these percentages are reflected in milliseconds.