title: Is x += a quicker than x = x + a?
body: <p>I was reading Stroustrup's "The C++ Programming Language", where he says that
  out of two ways to add something to a variable</p>
  
  <pre><code>x = x + a;
  </code></pre>
  
  <p>and</p>
  
  <pre><code>x += a;
  </code></pre>
  
  <p>He prefers <code>+=</code> because it is most likely better implemented. I think he means that it works faster too.<br>
  But does it really? If it depends on the compiler and other things, how do I check?  </p>