Types are the means of "improving language performance" without turning into C. It's all about encoding invariants for the optimizer. I doubt a competent JIT i

Types are the means of "improving language performance" without turning into C. It's all about encoding invariants for the optimizer. I doubt a competent JIT is ever slower than a competent interpreter, but it may not be that much faster or worth the workload. It depends on the size of the primitives. An array language could be close to 1:1, while for a cpu-level instructions you will struggle to reach 1/6 of JITted perf.