Why does my external monitor get x5 lower frame rate?

My frame rate is about 5x lower, and often unusuable on my external monitor (causes weird problems even for FixedUpdate). Unity version 2021.2.9f1 Personal, Apple Silicon version.

Anyone know why, and know a fix? This looks like a bug or something.

I am using a macbook pro M1 max, running on apple silicon, so maybe there is some issues there on the platform that haven’t been fixed yet?

Here is a video of the problem. Phone video due to it being on two screens: Unity - Low Frame Rate on External Monitor on Vimeo

Thats just how macbooks behave when you use an external monitor, i used to use one too.

The graphics cards are not really cut out for running two montors, nevermind 3D rendering.
I’d suggest using windows instead for this kind of work. You will run into much bigger problems than this further down the line on a macbook.
They are good for audio production and maybe some photoshop work but useless when it comes to 3D graphics and rendering