title: anonymous function performance in PHP
body: <p>I'm starting to use functional programming paradigms in php and was wondering what the performance impacts are.  Some googling just seems to say that there are some.  To be specific, I would like to know:</p>
  
  <ul>
  <li>Is there actually a performance impact or is it an urban legend?</li>
  <li>What is the performance impact (hopefully someone out that has done benchmarks)?</li>
  <li>What causes this impact (if one exists)?</li>
  <li>Is it fixed cost, or per execution?</li>
  </ul>
  
  <p>Any resources you guys have would be greatly appreciated :)</p>
  
  <p>Thanks in advance</p>