eh, not that much.

use.cpp:

    double rand_double() { return 16.; }
    int rand_int() { return 16; }
    void use(void*) { }

    #include <iostream>
    #include <chrono>

    void run();
    int main()
    {
      auto t0 = std::chrono::high_resolution_clock::now();
      for(int i = 0; i < 10000000; i++) {
        run();
      }
      auto t1 = std::chrono::high_resolution_clock::now();
      std::cout << std::chrono::duration_cast<std::chrono::milliseconds>(t1 - t0).count() << std::endl;
    }

    #include <cstdlib>

    int rand_int();
    void use(void*);
    void run()
    {
      auto res = malloc(rand_int());
      use(res);
      free(res);
    }

    #include <cmath>

    double rand_double();
    void use(void*);
    void run()
    {
      auto res = exp(rand_double());
      use(&res);
    }