Is there an example of the implementation of the CMS part on the code procedures?

Question

CMS

Show some example of the implementation of a part of the engine in php that uses procedural programming. As a beginner, it is not clear to me why my engine (namely, an include file with functions) uses so much memory, I'm trying to figure it out.
I would like to look, for example, at the implementation of the main page with access to the database.
How I do it:
Index.php includes a file with functions, then I set a condition for the url, and if there is only sample.com in the address bar, then header.php, home.php, footer.php are included. Main.php already uses functions for getting data from the database.
The site has several levels of pages, the database is also not quite small, and ~ 20 MB of memory is used. Why this amount of memory is used is not clear to me.

Answer 1

I don’t understand why I’m torturing myself with procedures, not in the sense of “what kind of bastards you are”, but in the sense - it’s so cool in objects, so beautiful and convenient, why the hell climbing home through the drainpipe every time when there is an elevator? There are just a couple of buttons to learn and you can ride! No need to beat your finger on the bedside table just because you are used to it and too lazy to move it!