PHP Configuration for Drupal 8

Hi guys,
I installed drupal8, for testing, on the same server where there are some sites built by me with Drupal 7.

I noticed that the Drupal8 site is very slow in loading the various pages.

What is the best php configuration for drupal 8 ?
Is there any particular configuration to be put in the PHP?

Thank you so much.

Drupal version: