title: Best practice to identify performance bottlenecks in a PHP/MySQL application (Drupal)
body: <p>I took over an app based on a heavily modified version of Drupal. The last developer didn't do a good job. At least at first sight I saw a lot of monkey-patching and things you should never ever do (password files, called password.txt, in a public webfolder, etc.).</p>
  
  <p>The app is incredibly slow. I guess it is caused by bad code (since it doesn't load large assets) and I guess it must be MySQL related - but I don't know for sure. </p>
  
  <p>Since the app is not documented, what would be the best and fastest approach to look for bottlenecks? Are there any tools that could help me? Where should I start? </p>
  
  <p>I pulled a version to run it locally on a Mac, maybe that makes things easier.</p>