Sometimes the site has an increased page load time, what could be the matter?

Question

Network administration

A couple of days ago I began to notice that when you load the site several times, the page load time can be more than 3-4 seconds, the same applies to adding comments, setting likes, etc.
What could be the problem? Maybe something needs to be cleared on the server? Or how to see what's stopping you?

Answer 1

look in top console
look at slow log in mysql