Low fps on external monitor connected to nvidia hdmi port

NVIDIA Open GPU Kernel Modules Version

555.42.02

Please confirm this issue does not happen with the proprietary driver (of the same version). This issue tracker is only for bugs specific to the open kernel driver.

• I confirm that this does not happen with the proprietary driver package.

Operating System and Version

Arch Linux

Kernel Release

6.9.3

Please confirm you are running a stable release kernel (e.g. not a -rc). We do not accept bug reports for unreleased kernels.

• I am running on a stable kernel release.

Hardware: GPU

AMD Radeon 780M IGPU + NVIDIA GeForce RTX 4060 Laptop DGPU (UUID: GPU-36f796c8-ee38-5be5-08a5-c7d8635be2d6)

Describe the bug

I have asus laptop with AMD Radeon 780M IGPU + NVIDIA GeForce RTX 4060 Mobile MAX-Q DGPU and KDE6 and Wayland session.
Laptop monitor connected to AMD GPU, external monitor connected to nvidia GPU (HDMI port).
When I run glxgears benchmark test in kde 6 wayland session on 555.42.02 nvidia-open driver or 555.42.02 nvidia proprietary driver without nvidia.NVreg_EnableGpuFirmware=0 kernel option on my external monitor connected to nvidia hdmi port I have low fps framerate equal to half the screen refresh rate (in my case I have only ~37-38 fps when external screen refresh rate 75).
This looks like a bug https://bugs.kde.org/show_bug.cgi?id=452219 but it nvidia diriver regression because on nvidia-open 550.xx driver or nvidia proprietary driver 555.42 drver wih nvidia.NVreg_EnableGpuFirmware=0 kernel option I have normal framerate on extenal monitor.
I can not use nvidia proprietary driver 550.xx or 555.42 because it causes the kernel to panic https://forums.developer.nvidia.com/t/series-550-freezes-laptop/284772/135 and nvidia can not fix this problem more than 3 monthes.
I do not want use nvidia open driver 550.xx because with this driver and external monitor I have very large cpu utilization for kwin_wayland proccess

To Reproduce

1. Connect external monitor to nvidia hdmi port, wayland, kwin 6 and nvidia-open driver 555.42.02
2. run glxgears on external monitor

Bug Incidence

Always

nvidia-bug-report.log.gz

nvidia-bug-report.log.gz

More Info

No response

Start by reproducing the issue with glxgears on the external monitor using Wayland, KWin 6, and nvidia-open 555.42.02. Inspect the attached nvidia-bug-report.log.gz and compare behavior across the 550.xx driver and the nvidia.NVreg_EnableGpuFirmware=0 option; done means identifying the 555.42.02 regression and restoring the monitor's expected refresh rate without the workaround.