This event is logged when Splunk sends data over the network. Data can be sent in two ways 1) cooked-when it is sent to another splunk instance and 2)uncooked-when it is being sent somewhere else like to a syslog server. My guess is this the log of a universal forwarder which is sending data to a Splunk indexer. The number of these events will scale proportional to the universal forwarders. They are benign and not a cause for concern. They are provided for informational reasons
Hmm. If there are no Warn or Error messages I don't think that it is anything benign for now. It could be caused by changes in the logging behavior/frequency of a particular log that is being monitored. In my opinion, keep an eye on your environment for more WARN or ERROR messages that would be a clearer indicator that something is wrong.
This is typically how it looks:
07-19-2016 15:18:53.994 -0500 INFO Metrics - group=thruput, name=cooked_output, instantaneous_kbps=0.300961, instantaneous_eps=0.354828, average_kbps=0.397792, total_k_processed=489797.000000, kb=9.330078, ev=11.000000