- Windows 11 October Update May Have Introduced a Nasty Gaming Bug
- This affects Nvidia GPUs and Team Green released a fix last week.
- However, we didn’t realize how bad the bug was, and testing shows that the frame rate can be huge – in Assassin’s Creed Shadows, it slows performance by 33% to 50%.
Nvidia released an emergency patch last week for an issue potentially caused by the Windows 11 October Update, and now we have some tests to highlight just how much of a major frame rate issue this bug was with some games.
Definitely, one game in particular. Digital Foundry has carried out tests with Shadows of Assassin’s Creedwhich was pointed out by many Windows 11 gamers complaining that Microsoft’s October patch (KB5066835) was seriously slowing down frame rates.
And those reports weren’t exaggerated, according to Digital Foundry’s benchmarking, which found that frame rates in Shadows of Assassin’s Creed were 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 coupled with an Nvidia RTX 5090 graphics card. Screenshots are provided for an instance where this powerful GPU was throttled down to 34fps (4K DLSS quality) with the patch applied, running at 72fps without the hindrances of the October update.
Nvidia neglected to specify which games were affected and required the emergency patch to save them, but it’s clear that Shadows was one of them. Digital Foundry observes that Counter-Strike 2 seems to be another title that takes a hit in terms of choppy frame rates.
Analysis: a mysteriously vague and rather nasty bug
It’s definitely a strange case, and it hasn’t helped that Nvidia has been vague when talking about this bug, simply saying that it hampers gaming performance with certain titles, without mentioning which games, or even what kind of performance issues are caused.
It’s really eye-opening to see tests like this reveal that the performance impact is so huge, at least for Shadows of Assassin’s Creed – this is a bug that can literally bring the RTX 5090 to its knees, as seen clearly illustrated. Good luck to an inferior Nvidia GPU.
At least there is a patch, but you have to find and install it manually (on Nvidia’s site) – and keep in mind that it’s a beta version. However, the fully tested and completed solution will be rolled out with the next Nvidia driver release.
If you’re not ready to get a beta version – and I would understand why, as this is also software that is not guaranteed to be cast so as not to throw other wrenches in the works – a suggested workaround is to disable the Resizable Bar feature (in the BIOS). This doesn’t completely alleviate the slowdown caused by the October update, but according to reports on Reddit, it minimizes frame rate drops.
The real question is: what is causing this problem? Nvidia indirectly suggests that it’s Microsoft’s fault, stating that the problem occurs “after updating to Windows 11 October 2025 KB5066835” – although this is not explicit blame. This doesn’t rule out an issue in Team Green’s drivers that was somehow exposed by changes Microsoft made in its update (AMD or Intel GPUs aren’t affected, after all).
We simply don’t know the root cause and overall the situation is far from ideal. It is possible that further investigations still need to be conducted by Microsoft or Nvidia, or even both companies. Regardless, I’ve reached out to Microsoft to see if the company can shed some light on why this happened, and I’ll update this article if I hear back.
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