Strange behavior of Open-Server. Why?

Question

open server

Hello! Please tell me what could be the problem... When working with Open-Server and while clicking on links on the site, sometimes there are "blunts", sometimes everything just opens instantly and sometimes you have to wait 5 seconds. I thought it was the site but then I created 2 empty html pages and just connected them with links, but the problem did not go away. Also, if you press and switch between them, then basically everything is always instantaneous, but sometimes (each can be 10 transitions) the same dullness happens. I have no idea what could be the problem. I googled and couldn't find the answer, or maybe I just didn't search very well.
I have a basic assembly and only Apache is included in the modules to work with PHP 7, and PHP 7 itself.
Thank you for your attention!