I think the article was saying that the javascript version of the google closure library is slower than the jvm based version so this would actually be a little bit slower.

Further, it has a serious restriction in that the version of cljs used by lumo itself is now the version of cljs that your project must use.

The cljs version is a pretty serious caveat but this seems like a really nice milestone on quite a bit of work. kudos to anmonteiro