A very simple Asteroids-style shooter, created in Unity 2021 Mac.
I deliberately avoided any kind of optimisation, as I was very curious to see what the impact would be on performance if I stuck to searching/finding/getting what was needed when it was needed, no matter how wasteful.
So every place you would expect there to be optimisation – looking up a component once and then storing the reference, storing references to arrays of created objects, and so on – there isn’t one.
Instead there are GetComponent<> and FindObjectByType<> and FindObjectsByType<> everywhere.