title: Dictionary comprehensions in python are too comprehensive
body: <p>Using python2.7 I found a weird time execution case:</p>
  
  <pre><code>data = dict( zip( a[0].split( ':' ), a[1].split( ':' ) ) )
  
  data = { name: value for name, value in zip(a[0].split( ':' ), a[1].split( ':' )) }
  </code></pre>
  
  <p>Those two calls seems absolutely the same to me, however, I found that the dictionary comprehension version is about 4% faster - not too much, but very stable.</p>
  
  <p>Is this true, and if so, why? Or is it just my imagination?</p>