Key is "well optimized". At some point and scale, it becomes almost impossible to chase those manual optimizations, not to mention that usage patterns at runtim

Key is "well optimized". At some point and scale, it becomes almost impossible to chase those manual optimizations, not to mention that usage patterns at runtime can change in such a way that make such an optimization prohibitively expensive, if not outright impossible. And even then, you would end up matching what the JVM JIT offers anyway. What I mentioned is already something that people have observed for both Rust and C++ against programs written in Java. Now add features like observability, profiling, debugging, and dev productivity, and it becomes a worthwile tradeoff a lot of the time. For constrained environments, GraalVM offers native image.