Hi, I would like to report a possible bug within Windows 11 (and probably Windows 10).
I have noticed that on laptops with Advanced NVIDIA Optimus technology running a Windows application in high performance mode (probably an UWP one like Phone or Scanner) causes GPU PCIE Rx and GPU PCIE Tx jump every few seconds from 0MB/s to 123MB/s, causing stutter to all applications running on integrated GPU.
It seems the stutter only affects applications running on integrated GPU, so every app on that will stutter for split of a second every 7-10-20 seconds.
It most often happens after disconnecting an external monitor, but it also happens when Windows 11 chooses high performance profile for a Windows app. I have also noticed that unplugging power might enhance this issue, while plugging power back might entirely stop the issue until power is unplugged again. When power is plugged, PCIE Rx/Tx return to 0MB/s state.
The reason why this issue appears is that when a stock Windows application runs on high performance mode, it is running through dGPU. This seems to cause random PCIE clogging, which causes stutter in applications running on iGPU.
That being said I also have stutters after unplugging external monitor with seemingly no application running on dGPU, so while the repro is most consistent when running a stock Windows app on dGPU, it doesn't seem to be the only way to cause the issue.
So far I have tried: different drivers, reinstalling windows, calling laptop's manufacturer service. Drivers didn't help. Windows reinstall didn't help. Manufacturer didn't find any issues with the hardware after thorough diagnostics (they have also changed motherboard and reinstalled Windows but it didn't help either).
From my research it seems this issue has not been in Windows 7. I have seen threads reporting similar issue in Windows 10 and 11.
Below I'm adding links to the videos showing issues.
Stutter after running a stock Windows app on dGPU: