So, you have a program that uses efficient algorithms with a well-parallelized implementation, and it’s neither I/O-bound nor memory-bound. Will it be faster in C? Yes, it very well might. It might also be faster in Fortran, which is why many continue to use it for scientific computation but that hardly makes it a good choice for more general use. Everyone thinks they’re writing the most performance-critical code in the world, but in reality maybe one in twenty programmers are writing code where anything short of the most egregious bloat and carelessness will affect the performance of the system overall.