Two fixes, one direct from Microsoft, and a new chipset driver from AMD, have arrived today, finally solving the performance problems that have dogged AMD's processors including the popular Ryzen line of chips, affecting in-game framerates severely in some cases.
The bugs were discovered after updating to Windows 11, and could cause upwards of 30% degradation in some situations, with a recent Windows update actually making the problem worse. The issue was all thanks to latency in the L3 cache and the incorrect assignment of CPU cores when running single-core workloads.
The L3 cache performance affects any application that relies on memory or cache latency, with video games being a primary example. Similarly, any games that are single-threaded, for example, may not use the CPU's "preferred core" (the fastest core on the processor) due to a bug that causes them to be assigned to other, less performant cores. This is causing issues especially on the higher core-count CPUs such as the 3900x and 5900x.
Thankfully, Windows 11 update KB5006746 fixes the performance issues with the L3 cache, while the new AMD Chipset Driver 3.10.08.506 resolves the preferred core issues. AMD has issued a statement stating that it has verified that the performance and behaviour of its chips are now as intended in Windows 11 following these updates being applied. AMD and Microsoft recommend that users promptly install this update on affected systems.
Both updates are now available through Windows Update, but be sure to check the Apps and Features section of Windows 11 settings to also grab the new AMD Chipset Driver package, which is available as an optional update.