title: Use tornado as websocket is too slow to process big file, can everybody help me to refine the performance
body: <p>I used tornado to receive file from client and found the process was too slow. I added log in tornado code, and found that the fllowing codes spent too long time on websocket.py-->WebSocketProtocol13-->_apply_mask function. <br/></p>
  
  <p>The code is:<br/>
  for i in xrange(len(data)):<br/>
  unmasked[i] = unmasked[i] ^ mask[i % 4]<br/></p>
  
  <p>Can everybody give me some idea about how to optimize it.</p>