title: PHP speed: what is faster? if (isset ($foo)) OR if ($foo==true)
body: <p>I am just trying to optimize my code.
  I need to prefill a form with data from a database, and I need to check if the variable exist to fill the text box (I don't like the <code>@</code> error hiding).
  The form is really long, then I need to check multiple times if the variables exist.</p>
  
  <p>What is faster of the following two?</p>
  
  <ul>
  <li><code>if (isset ($item))</code></li>
  <li><code>if ($item_exists==true)</code></li>
  </ul>
  
  <p>Or even</p>
  
  <ul>
  <li><code>if ($item_exists===true)</code></li>
  </ul>