You are right, my statement was a bit misleading. These Lua and Python based frameworks call the high performance implementation which is coded usually in C/C++

You are right, my statement was a bit misleading. These Lua and Python based frameworks call the high performance implementation which is coded usually in C/C++/Cuda/Fortran/etc. Nevertheless the Lua <-> C interface is lightweight and it certainly helps if the overhead is low. I know a guy who wrote a fast SAT solver in C, though called it with various slow bash scripts. I asked him why he uses bash, he mentioned it doesn't matter. In the end Microsoft's SAT solver beat him, exactly because they cared about such details too.