I currently have a AJAX heavy(almost everything) intranet webapp for a business. It is highly modularized(components and modules ala Joomla), with plenty of folders and files. ~ 80-100 different viewing pages (each very unique in it's own sense) on last count and will likely to increase in the near future.

I based around the design around commands and screens, the client request a command and sends the required data and receives the data that is displayed via javascript on the screen.

That said, there are generally two types of files, a display files with html, javascript, and a little php for templating. And also a php backend file with a single switch statement with actions such as, save, update and delete and maybe other function. There is very little code reuse.

Recently, I have been adding an server sided undo function that requires me to reuse some code. So, I took the chance to try out OOP but I notice that some functions are so simple, that creating a class, retrieving all the data then update all the related rows on the database seems like overkill for a simple action as speed is quite critical. Also I noticed there is only one class in an entire file.

So, what if the entire php is a class. So, between creating a class and methods, and using global variables and functions. Which is faster?