I just freshly installed  Centos 8  and Odoo 13  with Postgresql 3.6. No Nginx installed yet. No sample data. No any other application on the server. Also i didn't install any odoo application. 

To install odoo i folowed this step by step tutorial 

https://thestack.net/2020/03/How-to-install-ODOO-in-CentOS-8-RHEL-8.html

Server has 8 GB RAM and  2 CPU