The vast majority of benchmarks I've seen are down to LuaJIT performing specific optimizations out of the box that the C compiler used in the comparison can perform but doesn't.

In particular the last time I looked at LuaJIT vs C++ benchmarks, the C++ compiler flags weren't set allow the use of SIMD instructions by default, but LuaJIT does.

There was another recent example I saw where LuaJIT was calling C functions faster than C in a benchmark. Then someone pointed out what the LuaJIT interpreter was actually doing, and how to implement the same speed up in C.

Java people made the same arguments years ago: "Java is just as fast or faster than C++". You'll notice that after 20 years of comparisons, no one who writes high performance code for a living makes that claim.

It's true though. https://lmax-exchange.github.io/disruptor/files/Disruptor-1....

How many AAA game engines are written in Java?