“But even though the Optcarrot benchmark has shown impressive speedups, the JIT has not benefited real world business applications.”
Ruby’s first JIT made a benchmark fast and real apps no faster. The core team says so in the release notes. Shopify built YJIT to speed up its own Rails monolith, and it’s up to 22% faster on railsbench. The company with the money fixed the language for its own workload, and everyone else benefits.