Using an external display on an Apple silicon MacBook Pro laptop causes playmode FPS to drop significantly.
Repro:
1) Connect an external display to an Apple silicon-based MacBook Pro
2) Create an empty project. Make sure the scene view is not visible but the game view is. There's another, separate perf issue when showing both at the same time.
3) Enable the "Stats" button in the game view.
4) Enter play mode.
5) Move the game view between the built-in display and the external display. Leave it for a few seconds each time to let FPS stabilize. Note the values.
Result: Performance on the external display is very poor compared to the internal display
Expected: Much better performance on external displays