refs are not the highest performance reference type due to transactional semantics. ClojureScript already has efficient mutability in the form of atoms and tran

refs are not the highest performance reference type due to transactional semantics. ClojureScript already has efficient mutability in the form of atoms and transients. You can actually build a transient vector faster than you can build a mutable JavaScript array in recent builds of V8. I actually demo'ed this at JSConf. Fun stuff.