I remember this blog post about how optimizing method calls becomes much harder with refinements (from MRI Ruby 2.1):<p><a href="http:&#x2F;&#x2F;blog.headius.com&#x2F;2012&#x2F;11&#x2F;refining-ruby.html" rel="nofollow">http:&#x2F;&#x2F;blog.headius.com&#x2F;2012&#x2F;11&#x2F;refining-ruby.html</a><p>It looks like JRuby has refinements now but maybe not great support for them (based on just some quick Googling):<p><a href="https:&#x2F;&#x2F;github.com&#x2F;jruby&#x2F;jruby&#x2F;issues&#x2F;1062" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;jruby&#x2F;jruby&#x2F;issues&#x2F;1062</a><p>So I&#x27;m curious if anything tested in the article has refinements support.<p>Personally I&#x27;m still skeptical of refinements, but I guess JRuby will have to support them or more and more gems will start to break.