Joomla heavily(!) Loads the server! What could be?

Question

PHP

There is a site with low attendance (up to 500 visitors per day).
At first it was on joomla 1.5, then it was transferred to the last 3+
Now the pages are generated in 10 seconds, and if several users come in, it's generally hard!
I configured mysql so that all long queries fall into the log, all queries from this site fall there, but if you check through phpmyadmin, then these queries are executed very quickly (0.001 sec).
Caching configured, mysql driver - PDO. I temporarily added my crutch for caching the entire page for the guest in index.php, but this still does not solve the problem.
According to the standard profiler, I can’t understand anything at all, since I have never worked with joomla.
I set up headers in .htaccess so that statics are also cached by the browser.
Data from my cache crutch:

<!--/ Сгенирировано за: 10.874638080597 /-->
<!--/ Получено из кэша: 0.0036611557006836 /-->

And it's not right when one site on Joomla brings down a server with 40 cores and 64GB of RAM))))
Maybe someone has come across this?

Answer 1

I configured mysql so that all long queries fall into the log, all queries from this site fall there, but if you check through phpmyadmin, then these queries are executed very quickly (0.001 sec).

When you check requests - add after SELECT SQL_NO_CACHE. And show EXPLAIN of any long query.

Answer 2

1. redirects or external resources.
2. unnecessary / virus modules
3. idle caching system (in the admin panel, look at what is set for caching and then sort it out)
according to item 1 - check here: tools.pingdom.com/fpt
PS: If necessary, I can localize for inexpensive .. .

Answer 3

Joomla, Wordpress and other school site building tools have always loaded and will load the server more than necessary. But for them there are always the same heavyweight plugins that show what exactly in these CMS kills your server (sometimes these are the plugins).
And there is such a thing - caching, which can significantly reduce the load in 95% of cases. BUT schoolchildren who work with Joomla or Wordpress, unfortunately, do not like to read smart books. Otherwise, they would have switched to more flexible tools long ago.