Why such a difference in server response speed?

Question

PHP

Good day. The problem is this. There is an online store on prestashop, when you click on a link like example.com, it redirects to expample.com/index.php as the main page of the site.
example.com server response time around 100ms expample.com/index.php
server response time 500-800ms
What could be the problem? Everything lies on one server (1GHz, 1GB) nginx+php-fpm everything is controlled by VestaCP.
As I understand it, you need to dig towards php?

Answer 1

Because here example.com is just a redirect, and here expample.com/index.php is rendering the page

Answer 2

Because it costs nothing to give redirects, but it costs to generate a page