One thing that happened to more than one person (to me, too) is that when you upgrade your agents to 2.3.0 & enable the new way of connecting to the server, you might not have deactivated the agent encryption that was present before 2.3.0 already — ending up with two layers of encryption. Yes, that costs quite a bit of processing power. See the following:
That being said, this higher load would not be an hourly spike but higher load all of the time. Nevertheless, worth looking into.