Micro stuttering with HDMI dummy plug

I have ASUS TUF F17 laptop with Intel i7-12700H CPU and 2 GPUs with MUX switch - integrated and NVIDIA RTX 4060.
iGPU is bound to USB Thunderbolt port and an external 1920x1080 HDMI monitor is plugged in to it.
dGPU is bound to HDMI port and there is a dummy plug in it.

So I installed Looking Glass B7-rc1 with kvmfr module (128MB) and launched a game in a VM. It shows ~66 FPS but whenever I move camera it feels a bit odd, like micro stuttering.
However, if I keep Looking Glass running, then pull out dummy plug from dGPU port and plug in monitor to it, it feels super smooth as it should for this amount of FPS.

Is it something inherent to Looking Glass, or it can be fixed? I can buy an HDMI switch but it won’t be as convenient.