I mean, I ve literally thought about optimizing Rails by MJIT for over 3 years, and I ve introduced several optimizations designed for such workloads. We do rely on GCC to ease our maintenance, but the reason why it optimizes some benchmarks is that it implements various Ruby VM-level optimizations that donât really depend on GCC, not just that it uses GCC. Most of RTL-MJITâs optimizations were already ported to or experimented with YARV-MJIT after we shuffled the code to make it work with YARV, and itâs now faster than RTL-MJIT because of that and many other improvements after it.