I think this is incorrect, some features are by definition slower. Take for example the iterable protocol, it will always be slower than a traditional for loop

I think this is incorrect, some features are by definition slower. Take for example the iterable protocol, it will always be slower than a traditional for loop [1] because the spec mandates a prototype lookup and function call [2]. So far the only features that are actually fast are generators and the new data types (Map, Set, et al). [1] https://jsperf.com/for-vs-for-of/2 https://jsperf.com/for-vs-for-of/2 [2] https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Iteration_protocols https://developer.mozilla.org/en/docs/Web/JavaScript/Referen...