JRuby developer Charles Nutter claims that Java JDK7 gives a performance boost to JRuby, saying "On bench_threaded_reverse, Java 7 is 20% faster than Java 6, and JRuby plus invokedynamic is 20% faster than that".[1]

From http://en.wikipedia.org/wiki/JRuby with the [1] being

https://twitter.com/#!/headius/status/78282122997149696