Check out Ola Bini’s blog: Updated JRuby on Rails performance numbers. Excerpt:
…we are talking about 9.5s MRI to 13.8s for JRuby, which I find is a quite nice achievement if you look at the numbers from Friday. We are inching closer and closer. Both the view and the controller numbers are looking very nice. This is actually indicative of a nice trend - since general JRuby primitive performance is really good, the slowness in our Regular Expression engine is weighed up by much faster execution speed.
JRuby/MRI seems to be the metric that Ola’s focused on: his numbers give a ratio of 1.45 for Rails Petstore (13.8/9.5) on October 16th.
Take a look at this post to JRuby’s Dev list on Oct 4th from Christian Seiler: “JRuby vs MRI - Petstore shootout”. In it he charts the improvement between JRuby revision 4383 (sep 25th) and 4470 (early oct). And he demonstrates about a 20% performance improvement between those two revisions. On October 4th jRuby/MRI was 1.565 for Rails Petstore (29.89/19.10).
C. Nutter is also focused on Performance Updates.