AMD warns: CPUs run up to 15% slower with Windows 11

[German]The mass of computers is not yet ready for Windows 11 – and unpleasant surprises lurk around every corner. The processor manufacturer AMD has now informed that performance losses of 3-5% can definitely be expected for some chipsets and in other cases (for games) 10-15% under Windows 11. However, the processor manufacturer and Microsoft are working on updates that are still expected in October 2021.

There is currently a discussion about whether Windows 11 runs more quickly or more slowly on existing machines. I remember that a few weeks ago the story was passed around on the Internet that Windows 11 should feel more responsive due to an improved resource prioritization. I'm always very cautious about something like that – and it had already been mentioned at pcgamer.com that Windows 11 can cause a performance loss of up to 25% in the gaming area. Also the security features to ensure memory integrity via virtualization-based security (VBS) and Hypervisor-Protected Code Integrity (HVCI), costs some percent performance. This is also the reason for the Windows 11 limitation of CPU support, which directly support Mode Based Execution Control (MBEC) and do not emulate it. .

AMD issues a warning

Now processor manufacturer AMD has issued a documentation PA-400 that contains information about known performance degradations that have been reported in Windows® 11 when running compatible AMD processors with certain applications. 

• The AMD CPUs can cause extreme outliers in terms of performance degradation in eSports games, ranging from 10 to 15 percent. 
• For applications, AMD says the performance degradation is in the 3 to 5 percent range, as noted.

This affects processors supported by Windows 11: all Ryzen CPUs, all Zen+, Zen 2 and Zen 3 CPUs, also the Ryzen 2000, Ryzen 3000, Ryzen 4000 and Ryzen 5000 processors. In addition, according to the list linked above, select AMD EPYC processors for data centers and some newer Athlon chips are also affected.

Windows 11 Performance Changes on AMD CPUs, Source AMD

The performance losses are characterized by two problem categories. In the first line from the above figure, AMD writes that the measured and functional L3 latency can increase by about 3x. This has an impact on applications (3-5%) and games (10-15%).

And UEFI CPPC2 ("preferred core") may not preferentially schedule threads on the fastest core of a processor, which can also lead to a performance penalty. According to the figure above, AMD and Microsoft are working to alleviate these issues through a software update and a Windows update. Both are expected to be released before the end of October 2021.

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