This sounds like a very common situation to me. Over the last couple of years I have developed a realtime-monitor for GNU/LINUX. Measuring apache, MySQL, PHP, DRUPAL, JOOMLA, WORDPRESS, MAGENTO ... on the statement level. Tuning potential, e2e response-time, run-time, resource consumption. A project like yours has to be based on professional instrument. An APDEX dashboard will display your gains.