You do what you generally do with performance challenges: you profile and improve the hot-spots. Rewrite those parts if necessary. Rewriting everything for p

You do what you generally do with performance challenges: you profile and improve the hot-spots. Rewrite those parts if necessary. Rewriting everything for performance reasons is silly. If you decide to rewrite everything, it would be for other reasons (e.g. maintainability, long-term viability, etc.)