title: Foreach range iteration over a vector<int> - auto or auto&?
body: <p>Game engine micro-optimization situation: I'm using C++11 range for loop to iterate over a <code>vector&lt;int&gt;</code>, with the <code>auto</code> keyword.</p>
  
  <p>What is faster:</p>
  
  <pre><code>for(auto value : ints) ...
  </code></pre>
  
  <p>or</p>
  
  <pre><code>for(auto&amp; value : ints) ...
  </code></pre>
  
  <p>?</p>