My experience has been that JRuby 9k is slightly slower than MRI in a number of cases right now, mostly because its IR has been completely rewritten, and is sti

My experience has been that JRuby 9k is slightly slower than MRI in a number of cases right now, mostly because its IR has been completely rewritten, and is still pending a performance pass. That said, it's still a huge step up from the 1.7 series, and once the team starts knocking out performance problems it should be pretty magnificent.