Microsoft talks performance impact of Meltdown and Spectre patches on your PC

We're nearly a week out from the disclosure of Spectre and Meltdown, two major processor exploits that, between them, were revealed to impact nearly all modern processors. Microsoft and other companies have been quick to issue patches to address the exploits on their systems, but one of the major concerns that still remains is, due to how they work, how much those patches might affect performance. In a new blog post, Microsoft's Windows and Devices chief, Terry Myerson, has offered a preliminary take on what we can expect to see.

In short, if you're using a PC running Windows 10 on newer CPUs (Skylake, Kabylake, and newer), you likely won't notice much of a slowdown. Where the impact will be most felt is on Windows 8 and 7 machines on older CPUs and with Windows Server. Myerson explains:

  • 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.
  • 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.
  • 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.
  • 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.

Most companies have already issued some form of a fix for the issues, and Microsoft says it has patched 41 of the 45 Windows editions that it currently supports, with patches for the remaining editions to be released soon. That said, the process hasn't been without issues. Microsoft opted to pause the patch rollout for some older AMD systems after reports flooded in that the patch was making some Athlon-based PCs unbootable.

Going forward, Microsoft says it plans to perform benchmarks and publish them when available "in the weeks ahead." We should see a more granular look at exact performance impacts once all patches are out and comprehensive benchmarks are available. For now, you can read up further on the particulars of the exploits in Myerson's full blog post.

How to check if your PC is protected from the Meltdown and Spectre exploits