This is pretty unfortunate. At Facebook we use Object.freeze in a number of places to express POJSO immutability. A technique we've used to deal with the perfo

This is pretty unfortunate. At Facebook we use Object.freeze in a number of places to express POJSO immutability. A technique we've used to deal with the performance hit is to make most of these Object.freeze calls a no-op in a production environment. Most FB employees (incl non-devs) load the site in development mode, so we still get the stricter error messages.