Dual monitor causing FPS drops to half

My unity version is 2020 1.11

The issue is that if I use dual monitor (Win10, extend display mode) for unity editor, if I hit play the frame rate drops to half.

I have tried on multiple PC, laptop, all with a clean project, nothing added, same symptom
In profile, clearly whenever I use dual monitor layout for Unity Editor, there’s a huge long grey bar called “EditorLoop” appeared in Main Thread, without dual monitor, it disappear

Is this normal is if there’s anything that I can tweak?

The lowest spec rig I have tried is a surface pro i5 630, the 3D default project drops from 130 fps to 55 fps
The highest spec rig I have tried is a Zen 3600X with 2060, fps dropped from 550 to 300

Same issue here, tested 2019 and 2020 releases.

It’s on NVIDIA cards, not happening on AMD, you can workaround it with running Vulkan engine instead I realized,
for me that causing some other things, but it’s a viable workaround.

add -force-vulkan to switch from OpenGL to Vulkan.