First Windows 11 patch tuesday makes Ryzen L3 cache latency worse, AMD puts out fix dates

Shortly after Windows 11 launch, AMD and Microsoft jointly discovered that Windows 11 is poorly optimized for AMD Ryzen processors, which see significantly increased L3 cache latency, and the UEFI-CPPC2 (preferred cores mechanism) rendered not working. In our own testing, a Ryzen 7 2700X Pinnacle Ridge" processor, which typically posts an L3 cache latency of 10 ns, was tested to show a latency of 17 ns. This was made much worse with the October 12 patch Tuesday" update, driving up the latency to 31.9 ns.

That's one hell of a regression. It seems fixes are incoming soon, though.