title: fast XORing bytes in python 3
body: <p>I need to xor 2 bytes objects. I use this code:</p>
  
  <pre><code>def bxor(b1, b2): # use xor for bytes
      result = b""
      for b1, b2 in zip(b1, b2):
          result += bytes([b1 ^ b2])
      return result
  </code></pre>
  
  <p>It works fine when the bytes objects are small, but if I xor big objects (a few MB) it takes very long time (a few hours). How can I make it faster?</p>