approach – At first, an optimized byte-code is generated with ignoring rare/pathological cases – When needed, it is discarded and a naïve byte-code is regenerated – BTW: JRuby‘s boot time is too bad • OMR is not so fast? – JIT has no advantage? • Method calls and built-in methods may be still bottleneck – OMR seems not to support opt_case_dispatch yet • i.e., a case statement is not optimized well? 21