... how long are your build times? If your build times are high enough to really affect your productivity, I feel like there are much cheaper (and environmentally friendly) ways to halve them
Ditching SwiftUI and going back to Obj-C would absolutely slash my build times ;-) But who wants to do that!
The productivity gain is all about instant feedback and developer flow.
It might be hard to justify on paper to an IT Manager in charge of budgets when you add up the minutes.
But as I work for myself, it's easier.
As for environmental concerns, well, two year used Macbooks don't go in the trash. Used Macbooks have very long lives in my experience!
Still it could be a lot better.