[emidln]

Yes. Recent cljs using the nashorn repl anecdotally performs as well as unprofiled and unoptimized clojure for a bunch of common stuff I've tested. Theoretically you could reexpose the missing parts of the JVM clojure api to cljs on nashorn given that most of the missing parts of clojure are written in java. That would let you have things like the STM if you wanted them.