JRuby used to be much faster than MRI (definitely so when MRI 1.8 was current), but MRI has gotten better faster than JRuby, and IIRC, its now mostly a mixed bag based on workload, particular application design choices, etc.
That's generally not true. MRI's straight-line performance has not improved as fast as JRuby's, and if we're ever slower than MRI it's generally something we're doing wrong. When we're doing things right, performance can be anywhere from two to ten times faster than MRI.
