Meltdown and Spectre Windows fix cause performance slowdown especially on Windows 7

As detailed today by Terry Myerson, Executive Vice President of the Windows and Devices Group.

1) With Windows 10 on newer silicon (2016-era PCs with Skylake, Kabylake or newer CPU), benchmarks show single-digit slowdowns, but we don’t expect most users to notice a change because these percentages are reflected in milliseconds.

2) With Windows 10 on older silicon (2015-era PCs with Haswell or older CPU), some benchmarks show more significant slowdowns, and we expect that some users will notice a decrease in system performance.

3) With Windows 8 and Windows 7 on older silicon (2015-era PCs with Haswell or older CPU), we expect most users to notice a decrease in system performance.

4) Windows Server on any silicon, especially in any IO-intensive application, shows a more significant performance impact when you enable the mitigations to isolate untrusted code within a Windows Server instance. This is why you want to be careful to evaluate the risk of untrusted code for each Windows Server instance, and balance the security versus performance tradeoff for your environment.

"For context, on newer CPUs such as on Skylake and beyond, Intel has refined the instructions used to disable branch speculation to be more specific to indirect branches, reducing the overall performance penalty of the Spectre mitigation," Myerson said.

"Older versions of Windows have a larger performance impact because Windows 7 and Windows 8 have more user-kernel transitions because of legacy design decisions, such as all font rendering taking place in the kernel," the Microsoft exec added.

Based on the companys tests with Sysmark 2014 SE, 8th-generation Core platforms with an SSD inside will see a performance impact of 6 percent or less, Intel said, with specific test results showing a range from between 2 and 14 percent. The company said it did not have a comprehensive picture of how the patches would affect server workloads.²

Sources:

https://www.bleepingcomputer.com/news/microsoft/microsoft-performance-dip-on-old-windows-versions-due-meltdown-and-spectre-fixes/

² https://www.pcworld.com/article/3245742/components-processors/microsoft-tests-show-spectre-patches-drag-down-performance-on-older-pcs.html