Windows 11 is here, but it’s not in its best shape. AMD today issued an advisory warning of performance drops of up to 15% on AMD processors running Windows 11. AMD says it has an update expected to arrive later in October, but the company doesn’t has not yet announced the date.
Only certain applications are affected, but AMD did not specify which ones. Some apps show up to a 5% reduction in performance, while “games commonly used for esports” can show up to 15% degradation. AMD has also stated that thread-limited applications that demand a single core “may exhibit reduced performance.”
The problem stems from the increased latency of the Level 3 (L3) cache. AMD claims that Windows 11 can triple measured and functional latency. As the name suggests, this is the lowest level of cache, so increased latency here represents increased latency for the entire chip. The L3 cache powers the L2 cache, and so on.
Of course, this blockage applies to applications that rely on the processor memory subsystem. Esports titles like Dota 2 and Counter-Strike: Global Offensive are affected here because the data coming from your RAM in the processor is held by the L3 cache. Outside of games, other programs rely heavily on the memory subsystem, although they experience a much smaller drop in performance.
The second problem stems from AMD’s “preferred core” for limited threaded applications. AMD processors push the fastest core to the front of the stack in limited threaded applications, helping to improve performance by using the fastest core available. On Windows 11, it appears that the scheduler will not place any tasks on this kernel, which will result in decreased performance.
However, this problem does not apply to all processors. AMD says you should only notice a difference in processors with fewer than eight cores with a TDP above 65 watts.
These issues only apply to processors supported by Windows 11 – although it is possible that unsupported processors are affected as well. You can find the full list on the Microsoft website. For mainstream desktops, you are mainly looking for Ryzen 2000, Ryzen 3000, Ryzen 5000, Threadripper 2000, and Threadripper 3000.
We expected issues with Windows 11 at launch, but a 15% drop in some games is hard to swallow. It looks like there are issues with the Windows 11 Scheduler as well. Previously, we heard about Intel’s Thread Director feature and how the upcoming Alder Lake processors might take advantage of the Scheduler in Windows 11.
It seems that the planner has been tuned for this type of design. AMD and Microsoft are working on an update to fix the issue, but we don’t know when it will arrive yet. AMD says it is awaiting the update this month.
If you just installed Windows 11, you might want to take advantage of the 10 day downgrade period, at least until this issue is resolved.