Microsoft officially released the stable version of Windows 11 earlier this week. As it's common with new software, there are several known issues in the initial build. On Tuesday, Microsoft rolled out a new build that addressed some of these issues. However, one of the more glaring bugs remains: poor performance on AMD Ryzen processors. And the latest Windows update makes things even worse.

As it stands, many AMD processors run slower on Windows 11. Specifically, AMD processors are affected by two problems: increased L3 cache latency and the "preferred core" not working correctly. According to AMD's own investigation, performance impact could be as high as 15% in some games. When AMD officially confirmed the performance issue last week, it said the problem would be fixed in an upcoming Windows 11 update. Quite the contrary, the first Windows 11 patch has further worsened the performance issue.

According to TechPowerUp, the first cumulative update has further reduced the performance of AMD processors. The publication ran some tests on a Ryzen 7 2700X "Pinnacle Ridge" processor, which shows that the L3 cache latency has nearly doubled after the patch. Before the patch, the latency was in the vicinity of 17 ns. But now it has jumped to 31.9 ns. For reference, the latency was around 10 ns on Windows 10.

Similarly, Heise observed similar behavior in their testing on a Ryzen 5 5600G processor, recording a latency of 40 ns and 96 GB/s read and write throughput. In comparison, the same system had an L3 latency of 12.4 ns and read/write throughput up to 378 GB/s on Windows 10.

AMD says patches for the performance issues are ready and will be rolled out in the coming days. The L3 cache latency fix will arrive via the Windows Update channel on October 19. Meanwhile, the patch for the Preferred Cores (UEFI-CPPC2) will be released by AMD on October 21.

Screenshots courtesy: Heise