You realize with any modern C++ developer, they can program basically the same stuff, in the same number of lines modulo 4 lines of #includes?

    #include <numeric>
    #include <iostream>
    #include <chrono>
    #include <vector>
    
    int main(int argc, char** argv) {
      for (int i = 0; i < 15; i++) {
        std::vector<int> result;
        auto start = std::chrono::system_clock::now();
        for (int j = 0; j < 3000; j++) {
          result.push_back(i);
        }
        auto sum = std::accumulate(result.begin(), result.end(), 0);
        auto end = std::chrono::system_clock::now();
        std::cout << (end - start).count() << " " << sum << std::endl;
      }
    }

I think you underestimate what a multiple decades of coding 40hrs a week gives you in terms of development speed.