Problem with loading category page and paginator in category page

[Alex01-20]

1. Go to https://mcgroup.store/it/2-home

2.The loading of the page is slow

3. Change paginator to 2, 3 or n number

4. the loading of the page is slow

 

This is the problem:

https://calipio.com/app/play/wYOxV7ej#cRfG3egu

During the loading the cpu of the server goes to 100%

 

How can I fix it?

I have just activate the cache and delete it.

The site requirements are all respected.

I can't solve it in any way.

Please, help!