i’m using LibreNMS since September 2016. It is a great tool, better than other i tested before.
The configuración of the server is 2 processors with 6 cores each.
LibreNMs only shows 6 “CPUs” in the graphics, and the load only shows 1%, but the server is in a medium to heavy use every day.
In this server use as Operative System XenServer 6.0 with Openmanage.