SharePoint Site Rules deal specifically with the quantity of SharePoint sites or subsites in your SharePoint environment – excessive sites may degrade the performance of your SharePoint environment.

Deep Subsite Rules

These Rules check if the number of subsites exceed a certain threshold.

Excessive Site Rules

These Rules check if the number of top-level sites exceed a certain threshold.

Overloaded Web Site Rules

These Rules check if the number of sites with more than 2,000 web sites exceed a certain threshold.

There is a noticeable performance decrease when any site has more than 2,000 web sites.