Yajit

Ruby1.9 の bytecode => x86 / x86_64 の JIT

 Ruby1.8   0.72s user 0.03s system 98% cpu 0.766 total
 Ruby1.9   0.32s user 0.00s system 91% cpu 0.357 total
 Yajit     0.01s user 0.02s system 76% cpu 0.037 total

10倍速い!