title: PHP echo performance
body: <p>Which of these commands will perform the best? Worst? And why?</p>
  
  <pre><code>echo 'A: '.$a.' B: '.$b.' C: '.$c;
  
  echo 'A: ', $a, ' B: ', $b, ' C: ', $c;
  
  echo "A: $a B: $b C: $c";
  </code></pre>