I honestly think the best way of accomplishing performance is constraints. Constraints allow you to nip performance problems in the bud, they will show you exactly where the performance problems are without guesswork. This makes them much easier to fix than doing it after the fact. If your staging environment is a raspberry pi, I can almost guarantee you will not have performance problems on your production machine.

Also, with proper encapsulation, readability problems aren't that bad. With a clearly defined and well designed interface, you can always just do a new take on the implementation. I often produce fairly messy code when I prototype something, but since I keep interfaces in mind, it's almost never more than hour or two to clean up into something readable.