Performance issues can be caused by many things, from database interactions, web services, disk i/o and, less frequently, the code itself. We would typically turn to a profiler like xhprof to diagnose these issues, but what if the bottleneck is PHP itself, where do you turn? This talk will take that inspection a step further and look under the hood of PHP, at the C internals of how things tick. This talk covers what every PHP developer should know about their tools — like what’s really going on when you use double quotes vs single quotes. If you’ve ever wanted to know exactly what your code is doing, and why ++$i is faster than $i++, this talk is for you.