gettimeofday(&start_time, NULL);
return_code= world.runner->run(run->test_fn, world_ptr);
gettimeofday(&end_time, NULL);
load_time= timedif(end_time, start_time);
gettimeofday(&start_time, NULL);
return_code= world.runner->run(run->test_fn, world_ptr);
gettimeofday(&end_time, NULL);
load_time= timedif(end_time, start_time);