Windows 11 update fixes AMD performance issues

A new Windows 11 update appears to have fixed some of the performance issues on PCs running AMD Ryzen processors.

Soon after the launch of the new operating system on 5 October, AMD published a tech support document stating that it was aware of two performance changes that its processors might exhibit while running Windows 11.

One of these would result in measured and functional Level 3 (L3) cache latency increasing approximately three-fold.

Applications sensitive to memory subsystem access time would take a 3-5% performance hit. However, AMD said 10-15% outliers were also observed in popular eSports games.

Put simply, it resulted in big frame drops in several games compared to the same systems running Windows 10.

A Patch Tuesday update on 12 October made the problem worse, with TechPowerUp finding it increased latency by almost twice as much.

Fortunately, last week, Microsoft rolled out developer and beta versions of a patch for the issue called KB5006746.

Benchmarking tool AIDA64 ran tests on it and found that the latency issue was fixed.

The screenshots below show the performance of the L3 cache before and after the update, showing a marked improvement.


Microsoft’s official patch, released on Tuesday, 19 October 2021, acknowledges that it fixed the issue.

AMD is set to roll out a driver update on Thursday, 21 October, to address the second performance change.

That should fix an issue where the UEFI CPPC2 (“preferred core”) does not preferentially schedule threads on a processor’s fastest core.

AMD said that applications sensitive to the performance of one or a few CPU threads might exhibit reduced performance because of this issue.

This impact may be particularly noticeable in processors with more than eight cores and a thermal design power (TDP) of over 65W.

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Windows 11 update fixes AMD performance issues