The load on the server because of the parser: how to watch?

Hello!
For page party variable data (about 4 lines each) with four other sites using Php Simple DOM.
Each site parses individual, made me a php file. On the page the data is displayed using:
<?php
 $content = file_get_contents('https://site.ru/parser.php');
echo iconv("UTF-8", "UTF-8", $content);
?>

Such requests-conclusions four on the page.

In the error-logs show different errors: either the unavailability of the donor site (oceny rarely) or the lack of information in the rows (which is not critical), but the parser works and displays everything.

The question is:
How to watch the total load on hosting (and will it), because if the request of my page a couple of times a day and parser run too a couple of times, it is not critical, but if the attendance page is a multiple of the increase, and even hundreds of queries at the same time? What server settings will need to tighten or library to put?
June 8th 19 at 17:10
1 answer
June 8th 19 at 17:12
Optimizations nothing special and won't make different what to increase the number of threads PHR
And just keep the sites to a disc and give the disc and on the domain are updated every five minutes for the crown

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