I have an older Mac Mini, and I wanted to run it headless to play my music through iTunes.
The problem is that the performance for screen sharing without a monitor on the host is abysmal.
The solution is to trick your ?Mini into thinking it does have a head so it loads all QT and fires up it’s GPU.
A few resistors from Radio Shack (yeah, they can still be relevant) and a spare VGA adapter are all you need.
The adapter
The pins to be jumped.
The resistors in place.
Plug it in and enjoy the full performance potential of your Mini.