Do you have an iGPU+dGPU combo like in a gaming laptop? For my 2019 gaming laptop with a i915+RTX2060, if I leave the switchable option on in the hardware settings (meaning the OS can choose which GPU to use ie. iGPU for low power), I end up with similar behavior in Linux/Win10. The external port actually uses the dGPU so rendering must go through it but it will struggle with the switchable option and I end up with freezing or stutters. In Linux, I explicitly configure Xorg to only use the iGPU and reserve the dGPU for model inference which fixes the stuttering issue. When booting into Win10, I explicitly disable the iGPU and turn off the external monitor so my VR playing doesn't stutter or youtube doesn't freeze or stutter.