On Xcode 15 release version 15.0 (15A240d) the iOS 17 Simulator is very slow when running SpriteKit apps. The fps barely gets over 15 fps and everything is lagging. This is unusable for testing games. (M1 Mac mini 16GB RAM)
diagnosticd and SpringBoard seem to be hogging the processor. This continues whether debugging is attached but also when the Simulator is idle.
It does not matter which type of device is used. iOS 16 and lower Simulators are fine.
In the previous version everything was fast and smooth, I could run 4 or 5 simulators at the same time with SpriteKit games.
What to do?
[edit: updated it only occurs on iOS 17 Simulators.]