Performance Monitoring gives you a hint on the ping of your monitored IP. This can help you understand if your network is being overloaded at that moment.
The network performance setting can be configured in the "Server Admin > Endpoint Policies > System > Network" section of the Web App UI.
You can also configure this setting on the VSA10 Agent itself. However, the Web App Policy settings (if applied to the same machine) will always take precedence over the individual agent settings.
Also, Policies are naturally more convenient for applying such monitoring rules, as they can be applied to multiple machines simultaneously.
To configure this setting on the Agent, go to the "System > Network > Performance" tab.