OS-level threading is often pretty good -- you can usually fork and join tens of thousands of threads per second. (I believe that the initial NPTL benchmarks sh

OS-level threading is often pretty good -- you can usually fork and join tens of thousands of threads per second. (I believe that the initial NPTL benchmarks showed something like 20 microseconds for thread spawn.) It's not the tens of millions per second that you get with green threads, but thread creation has an unfair reputation of being slow. It was once true, but that was 20 years ago.