Both. Scale in performance, since dynamically typed languages have fundamental hurdles that will always make programs slower than when written in a statically

Both. Scale in performance, since dynamically typed languages have fundamental hurdles that will always make programs slower than when written in a statically typed language. And scale in code base and developer strain. The fact that it's mathematically impossible to reliably refactor code automatically if the types are absent encourage spaghetti code bases that developers are afraid to modify because they can never be sure they're not breaking anything. Such hesitations never happen in statically typed languages.