My CPU usage has increased, disk storage under stress, Splunkd very busy in the last few days? Does MC or Splunk Admin apps or even Meta Woot! help to find the hogs in my environment eating resources?
If you enable Forwarder Monitoring on the DMC it will show you the connected forwarders, total KB sent, avg KB sent, avg events sent, and more. This sounds like what you're looking for.
Documentation:
https://docs.splunk.com/Documentation/Splunk/8.2.1/DMC/ForwardersDeployment