Windows 11 reduces performance of AMD Ryzen processors by up to 15 per cent
A fix is expected to come later this month
Windows 11, the latest version of Microsoft's Windows operating OS, has an issue with AMD processors and could cause substantial performance drops in some cases.
The warning comes via a support document by AMD, indicating that all AMD chips officially compatible with Windows 11 are affected.
For consumers, these processors go back to 2018's Ryzen 2000 series.
According to AMD, two separate bugs have been identified in Windows 11 that can reduce performance for Ryzen processors by as much as 15 per cent. How much drop in performance the user will observe will vary based on the application being run and the CPU being used by the user.
The first issue AMD and Microsoft have identified may cause L3 cache latency to triple, affecting applications that rely on fast memory performance.
According to AMD, most affected apps will show a performance drop between 3 and 5 per cent, although some "games commonly used for eSports" could slow down by between 10 and 15 per cent.
Microsoft is expected to roll out a fix for the issue later this month via a Windows update.
The second bug is related to AMD's UEFI CPPC2 ("preferred core") feature which directs single-threaded tasks to the fastest two cores on the chip, rather than treating all cores the same.
It appears that Windows 11 is ignoring the "preferred cores" system and picking less optimal cores to perform the task.
According to AMD, the issue would primarily impact performance in lightly-threaded applications, and the dip in performance may be noticeable in processors with eight or more cores and a 65 W or higher TDP. This would include most 2000, 3000, 4000, and 5000-series Ryzen 7 and Ryzen 9 desktop CPUs and APUs.
AMD says the issue would be addressed through a "software update," not a Windows update, which will be rolled out later this month. That means you may need to install new AMD chipset drivers or some other software to get the fix.
AMD is also advising that its customers experiencing the issues can "continue to use a supported version of Windows 10" - suggesting that it probably best to delay upgrading to Windows 11 until the issues are fixed.
Notably, these issues are separate from performance slowdowns caused by Microsoft's recommended VBS and HVCI security settings. In particular, tests conducted by Tom's Hardware showed that the Memory Integrity security feature can decrease performance by a few percentage points in some games and general computing tasks.
The results showed the performance drop would vary depending on the processor and software used.