title: Multiprocessing output slower than single process
body: <p>I'm running this code, and it seems running the script using multiprocesses is slower than running it via a single process.</p>
  
  <p>Am I doing something wrong?</p>
  
  <pre><code>from time import time
  numbers = [(1963309, 2265973), (2030677, 3814172),
             (1551645, 2229620), (2039045, 2020802)]
  start = time()
  results = list(map(gcd, numbers))
  print(results)
  end = time()
  
  
  print('time is %.3f'%(end - start))
  
  from multiprocessing import Pool
  
  
  if __name__ == '__main__':
      start = time()
      with Pool(4) as p:
        print(p.map(gcd, numbers))
      end = time()
      #print('time is %.3f'%(end - start))
      print('Took %.3f seconds' % (end - start))
  </code></pre>
  
  <p>output is </p>
  
  <pre><code>[1, 1, 5, 1]   # single process
  time is 0.444
  [1, 1, 5, 1]   #multi-processes
  Took 0.751 seconds
  </code></pre>
  
  <p>Thank you. </p>