It's funny, the path software technology takes. A Java clone of a fairly basic web engine (which is a fairly simple application type to begin with) convinces people to try the JVM which is the most performant managed runtime around and definitely one of the most advanced pieces of software ever created. I'm sometimes amazed that and people coming from easy-to-use web languages have never been exposed to it, and if they have they still have their doubts.

Dude, I've been developing real-time military applications and we've moved from C/C++ to Java and got performance gains (I'm not saying that C can't beat Java doing specific computations - of course it can - but when building a large application with millions of lines of code and a large team of developers, Java would be a safer bet than C++ if speed is your concern). In other words, no other environment can beat the JVM.

And, yeah, you should try Clojure. It's a cathartic experience.

EDIT: The only doubts I have about vert.x is that it can consistently beat "old" JVM servlet containers under heavy, real-world loads. That remains to be seen.