Map and Set iterators are now way faster in V8, up to 11x (as per @bterlson's request) 

http://benediktmeurer.de/2017/07/14/faster-collection-iterators/ …pic.twitter.com/KOcO57PB5I
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You mean for iteration?
Any of the operations, really.
Good question for @_gsathya 
Objects and collections will have the same backing store soon so they shouldn't be different
Strings don't undergo the hidden class transition when added to collections as they store the hash in an internal field
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