I've been working on Swift game which is not yet launched or available for preview.
The game works in such a way that it has idle CPU while the user is thinking and sustained max CPU and GPU on as many cores as possible when he makes a move.
Rarely, due to OS activity or something else outside of my control (for example when dropping the OS curtain even if for just a bit then remove it), the game or some of its threads are moved to efficiency cores which results in major stuttering which persists precisely until the game is idle again at which point the game is moved back on performance cores - but if the player keeps making moves the stuttering simply won't go away and so I guess compuptation is locked onto efficiency cores.
The issue does not reproduce on MacCatalyst on Intel.
How do I tell Swift to avoid efficiency cores?
BTW Swift and SceneKIT have AMAZING performance especially when compared to others.