How to optimize and shorten PHP code?

Question

PHP

Good evening. There is the following code:
https://pastebin.com/RMKtcpH1
The first part of the code up to line 47 is to assemble the $result array with the catalog product SKUs.
The second part of the code, after 47 lines, iterates over the $result array and displays detailed information about each product by article.
There are about 20,000 items.
There was a problem right away. When you try to execute this code, the script starts to load for a long time and eventually the error 504 Gateway Timeout
gets out The page where this error comes out - 93.90.220.244/get/treolan_productslist.php

Answer 1

What is written in the answer above, plus
Find out if the service has the ability to request many records at once.
Cache information whenever possible.