Since you might have a lot o f domains across your IDGs you should choose a set of domains.
We can focus you on the TOP 5 (Or TOP 10) domain activity . Please remember that if you have in 2 IDG's 2 domain with the same name - They will be aggregated unless you filter by device.
Let assume you want to focus on the TOP 5 Domains:
Goto Dashboards → Recent Activity .
Set Time Filter to 5 minutes (this is usually generates a 1 sec interval).
You will see at the bottom a table labeled with Domain Activity (Top 5) - see marked in green
Set Domain Filter to each of the domain .
You will see your time series on the System Activity - Marked in Red