Chris Shiflett, after finding an old reference guide, has decided to share a few helpful hints from the guide to help you in your development.
While cleaning out my desk, I found an old copy of a PHP Quick Reference I helped make a few years ago. On the front page are a few performance and security tips that I thought I'd share. (Performance tips are from George Schlossnagle.)
The tips include topics like caching, using external data sources, filtering input using prepared statements and using pre-existing solutions before just rolling your own.