For 4-cores CPU running 64-bit Linux with Python 2.6: * single-threaded: 7.6s * two threads: 8.8s * 4 threads: 9.14s * 4 processes (via multi

For 4-cores CPU running 64-bit Linux with Python 2.6: * single-threaded: 7.6s * two threads: 8.8s * 4 threads: 9.14s * 4 processes (via multiprocessing) 2.0s Overhead is ~16-20% (5% for multiprocessing) #!/usr/bin/env python from threading import Thread from multiprocessing import Process def countdown(n): while n > 0: n -= 1 COUNT = 100000000 def run_once(): countdown(COUNT) def run_with_threads(nthreads, make_thread=Process): threads = [make_thread(target=countdown, args=(COUNT//nthreads,)) for _ in range(nthreads)] for t in threads: t.start() for t in threads: t.join()