Overall, as expected, given its base on solid Java technologies, Grails out performs Rails (100% Ruby) in pretty much every test. As I said at the start I'm no Rails performance tuning wizard, so if someone can suggest ways to get Rails to perform better please say so. We are conducting these tests purely to inform concerned Grails users who are asking for figures, and hope to review them as Grails progresses. Interestingly, Grails, at least on this machine, sees performance increases when lowering the thread pool to 10, whilst Rails suffers when 10 mongrels are configured with Pound. Grails hasn't undergone much optimisation at all yet and there are certainly areas we can improve on, GSP rendering being one. GSP is of course a much more complex view rendering technology in comparison to RHTML due to its support for dynamic tag libraries, plus Sitemesh decoration. However, there are definitely areas in GSP, such as the way it uses exceptions, that can be improved upon. Another point to remember is performance != scalability. The way you would scale an application to deal with the kind of load we have here differs greatly between Grails & Rails I imagine. With Grails you could stick a Terracotta or Coherence distributed cache on the back of it to implement SSI (singe system image) or use HTTP session replication across a cluster whilst with Rails you could ??? (a Rails user please feel free to provide an answer to this question in the comments, I'm not qualified to answer). Nevertheless, I am quite satisfied that Grails performs sufficiently well to be competitive and there is little point in optimising prematurely. Our main goals is to focus on getting 1.0 out towards the middle of this year.