> InvokeDynamic support<p>This is the big one, in my opinion. See here[1] for some benchmarks of JRuby + invokedynamic. We're talking orders of magnitude for some benchmarks.<p>[1] <a href="http://blog.headius.com/2011/08/invokedynamic-in-jruby-constant-lookup.html" rel="nofollow">http://blog.headius.com/2011/08/invokedynamic-in-jruby-const...</a>
Biggest things stopping me from using jruby:<p>1. Incomplete integration with postgresql. The ActiveRecord jdbc adapater doesn't have all the features that the standard pg adapter does.<p>2. Slow startup / test runs. At one point, loading large amounts of files (like during rails bootup) was much slower on jruby than MRI.
Looking forward to installing it and trying it out with Torquebox ( <a href="http://torquebox.org/" rel="nofollow">http://torquebox.org/</a> ) for a new project.