title: PHP Opcode Caching/Zend Acceleration and include_once vs. require_once
body: <p>I have a colleague who is looking into opcode caching/Zend Acceleration (I've always assumed these are the same thing) for our PHP based application.  His Benchmarks appear to indicate that we're NOT seeing a performance benefit if we include our (large) class libraries with require_once, but we DO see the performance benefit when using include_once. </p>
  
  <p>This smells fishy to both of us, but I don't have time to check into our benchmark methodology myself and my colleague has more tolerance for the smell of fish than I do. :)</p>
  
  <p>Has anyone ever run into anything like this? If not, any thoughts on other things that might be causing the appearance of a performance increase by switching from include_once to require_once?</p>