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.