I decided optimized, clean, efficient as my PHP code is, others could ultimately code something just as good or better.
Partly because of that, but also because I like to be helpful, I have decided to lift the lid on some of the core PHP which I use.
I have made this available here:
http://codebox.johndriscoll.co.uk/
Any code you find there is free for commercial and personal use. Accessibility of material there is at my discretion.