- Windows 11 October Update May Have Introduced a Nasty Gaming Bug
- It affects Nvidia GPUs and Team Green released a hotfix last week
- However, we didn’t realize how bad the bug was, and testing shows that the impact on frame rates can be huge: in Assassin’s Creed Shadows, it reduces performance by 33% to 50%.
Nvidia released an emergency fix last week for an issue potentially caused by the Windows 11 October Update, and now we have some evidence to underline what a major headache this frame rate bug was in some games.
Without a doubt, a particular game. Digital Foundry ran some tests with Assassin’s Creed Shadowswhich was highlighted by many Windows 11 players complaining that Microsoft’s October patch (KB5066835) was seriously slowing down the frame rate.
And those reports weren’t exaggerated, according to Digital Foundry’s benchmarking, which found that frame rates on Assassin’s Creed Shadows They slowed down by at least 33% and up to 50% or more in the worst cases.
This was on a gaming PC with a Ryzen 7 9800X3D processor paired with an Nvidia RTX 5090 graphics card. Screenshot evidence is provided of a case where this powerful GPU was down to 34 frames per second (4K DLSS quality) with the patch applied, running at 72fps without the shackles of the October update.
Nvidia didn’t say which games were affected and required the emergency hotfix to rescue them, but it’s pretty clear that Darkness was one of them. Digital Foundry notes that Counterattack 2 It appears to be another title that suffers in terms of choppy frame rates.
Analysis: A mysteriously vague and rather unpleasant bug
This is a strange issue, really, and it hasn’t helped that Nvidia has been vague about this bug, simply saying that it hinders gaming performance with some titles, without mentioning which games, or even what kind of performance issues are caused.
It’s really eye-opening to see that tests like this reveal that the performance hit is so big, at least for Assassin’s Creed Shadows – this is a technical issue that can literally bring the RTX 5090 to its knees, as we see clearly illustrated. Good luck to a lesser Nvidia GPU.
At least there is a solution, although you have to find and install it manually (on the Nvidia site), and keep in mind that it is a beta version. However, the fully tested and finished solution will be implemented with the next Nvidia driver release.
If you are not willing to get a beta version, and you would understand why, as this is equally non-cast iron software and guaranteed not to complicate the process further, a suggested solution is to disable the resizable bar feature (in the BIOS). This doesn’t completely mitigate the slowdown caused by the October update, but according to reports on Reddit, it does minimize any drop in frame rate.
The real question is: what caused this problem? Nvidia indirectly suggests that it’s Microsoft’s fault, stating that the issue occurs “after updating to Windows 11 October 2025 KB5066835,” although that’s not an explicit sign of fault. It doesn’t rule out an issue in the Team Green drivers that was somehow exposed by the changes Microsoft made in its update (after all, AMD or Intel GPUs are not affected).
We simply don’t know the root cause and overall this is a situation that is not ideal. Microsoft or Nvidia, or even both companies, may still need to conduct deeper investigations. In any case, I’ve reached out to Microsoft to see if the company can shed some light on why this happened and will update this article if I hear back.
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