Finally, Microsoft and AMD have released two updates, dedicated respectively to Windows 11 and chipset drivers, which they should solve problems AMD Ryzen processor L3 cache latency, resulting in a decline in performance on PCs with AMD CPU and Windows 11 operating system. The two bugs affected all AMD Ryzen processors compatible with Windows 11 and based on Zen + architecture, Zen 2 and Zen 3, i.e. all Ryzen generations from 2000 to 5000, as well as some chips Latest AMD Epyc and Athlon.
There were two bugs that caused the problems and one was fixed by AMD, the other by Microsoft. The fix released by AMD is inside the new chipset drivers, available for download at this address, and fix the problems related to the UEFI CPPC2 driver. The patch published by Microsoft resolves the problems related to L3 cache latency and bandwidth.
This means that in order to get full performance from your computer again, you will need to install both updates. The UEFI CPPC2 driver bug (which stands for "Collaborative Power and Performance Control 2") caused AMD's technology that deals with moving lighter loads to faster processor cores to malfunction, leading to degraded performance especially in software that use a few threads. According to AMD, the problem was more visible in CPUs with more than 8 cores and a TDP above 65W, however with the chipset driver update released today, you can go back to sleep peacefully even if you have a processor with these characteristics.
The Windows update that fixes the latency and bandwidth issues is instead identified by the code KB5006746 and brings the Windows 11 version to build 22000.282. The problem, according to Tom's Hardware US tests, could cause a up to sixfold increase in latency compared to that recorded with Windows 10, moreover the bandwidth was up to twelve times higher with the old operating system. According to reports from AMD, this could cause a performance call of up to 15% in some esports games and 3-5% in other applications. The tests of the American colleagues did not report particular variations in the performance in the game, but it is still good that the problem was solved fairly quickly.