title: is the + operator less performant than StringBuffer.append()
body: <p>On my team, we usually do string concatentation like this:</p>
  
  <pre><code>var url = // some dynamically generated URL
  var sb = new StringBuffer();
  sb.append("&lt;a href='").append(url).append("'&gt;click here&lt;/a&gt;");
  </code></pre>
  
  <p>Obviously the following is much more readable:</p>
  
  <pre><code>var url = // some dynamically generated URL
  var sb = "&lt;a href='" + url + "'&gt;click here&lt;/a&gt;";
  </code></pre>
  
  <p>But the JS experts claim that the <code>+</code> operator is less performant than <code>StringBuffer.append()</code>. Is this really true?</p>