The polyfilling is only necessary for IE10 and lower. Many people who are conscious about size don't support old browsers so that's a real win for them. You co

The polyfilling is only necessary for IE10 and lower. Many people who are conscious about size don't support old browsers so that's a real win for them. You could also include polyfills conditionally by sniffing the user agent. I'm also fairly sure there exist smaller polyfills for Map and Set. We should probably look for them and suggest them instead.