A Windows 11 update just broke one of the biggest new games — and even top-end PCs weren’t safe. If you’ve recently noticed Assassin’s Creed Shadows stuttering or losing frames, you’re not alone. Microsoft’s October Windows 11 update, known as KB5066835, unexpectedly sent gaming performance nosediving — in some cases by nearly half. But what exactly went wrong, and how can you fix it? Let’s dig into the details.
Windows 11 update tanks Assassin’s Creed Shadows performance
When Microsoft rolled out its October patch for Windows 11, it unintentionally unleashed chaos for gamers. High-end systems that should have no trouble running Assassin’s Creed Shadows — including setups using an AMD Ryzen 7800X3D processor and Nvidia’s GeForce RTX 5090 graphics card — suddenly saw massive frame rate drops. In tests by Digital Foundry, frame rates plummeted from a smooth 72 frames per second (FPS) to barely 34 FPS after installing the update. That’s a drop of nearly 50%, turning a previously flawless experience into a lag-filled slog.
Even top-tier rigs couldn’t escape
What made this issue especially alarming was that it affected the most powerful builds on the market. Reports flooded in from frustrated players on Steam’s community forums, describing severe slowdowns after applying the update. And it wasn’t just Assassin’s Creed Shadows — some Counter-Strike 2 players began complaining of jittery gameplay and strange performance dips as well.
Still, no one — not even Microsoft or Nvidia — provided a clear list of which other games were suffering similar issues. Nvidia did, however, confirm the existence of the bug in a public statement. The company warned that the October Windows 11 updates for versions 24H2 and 25H2 “may lead to lower performance in some games.”
Nvidia rushes to release a fix
Fortunately, Nvidia didn’t waste time. It quickly pushed out an emergency GPU driver hotfix that rolled performance back to normal across affected titles. Players who installed the hotfix reported immediate improvements, restoring their games to pre-update smoothness. If you’ve been pulling your hair out wondering why your system suddenly slowed down, this patch might be your lifeline.
What’s actually causing the slowdown?
Here’s where it gets a bit murky — and controversial. Digital Foundry’s team tried to uncover the exact cause but couldn’t reach a definitive conclusion. Some experts suspect Microsoft’s update patched a vulnerability that inadvertently interfered with GPU communication or driver efficiency. Others believe a compatibility conflict occurred during the update process itself, especially between Windows’ kernel-level changes and Nvidia’s new driver stack. Interestingly, Nvidia’s statement tiptoed around assigning blame, suggesting the cause might not rest solely with Microsoft. Could both companies share responsibility? That’s an ongoing debate.
How to fix Assassin’s Creed Shadows performance issues
If you’re dealing with choppy gameplay or plummeting FPS, there’s a simple fix: download and install Nvidia’s emergency GPU hotfix driver. This quick patch has proven to restore most systems to full performance. Gamers using Windows 11 24H2 or 25H2 should especially take note. Until Microsoft provides further clarification, updating your Nvidia drivers is the most reliable way to reclaim smooth frame rates.
The bigger picture
This situation serves as a powerful reminder: even official Windows updates can unintentionally harm gaming performance. Each update cycle sometimes introduces new bugs or compatibility hiccups that escape testing — especially when cutting-edge hardware like the RTX 5090 is involved. It raises a broader question for the community: Should Microsoft slow its update schedule to prevent these kinds of gaming disruptions, or is the risk worth the benefit of faster security improvements? What side are you on — stability or speed? Drop your thoughts below and let the debate begin.
