On typical site performance audits, I'm usually given a summary of the problems from the developers of the site. About 80% of the time this information is wrong.

As developers, we have a tendency to be remarkably unscientific when analyzing performance issues. We like to look first at hardware or software configuration issues, which are usually the most difficult to measure and beyond the scope of a typical developer's skill set. We then like to suggest solutions to problems based on evidence that is anecdotal, based on intuition, or if actual data was collected, is measuring the wrong thing. This inevitably leads to premature optimization, micro-optimization, or simply solving problems you don't have, all of which add complexity to your infrastructure.

In this session, I'll discuss:

How I approach a new site to get an unbiased perspective
The methods and tools I use to collect and analyze data to diagnose performance issues
Mark works as a performance engineer at Acquia. He is the author of the XHProf drupal module, XHProfLib, xhprof.me, and is a member of the Drush core team. Past presentations include:

Profiling Drupal with XHProf (at BADCamp, PNWDS, New York, and Austin)
Configuration Management with Chef
Advanced Drush