Ah. Is it possible that you clicked the validate checkbox on a script that contained an infinite loop while you were developing?
With your CPU usage being high, we should be able to get more information what's occurring with some thread dumps. You can navigate to
http://host:port/rest/v1/threads?asFile=true&stackDepth=40 and post the result. I'll run a python script to parse and sort it, as I did here: https://forum.infiniteautomation.com/topic/3292/very-high-cpu-usage (this user had caused an infinite loop to run in a script validation, which the solution for is restarting Mango). I've certainly seen high CPU usages on instances that had very large events tables, too, which can be purged on the system settings page.
That warning is unlikely to be the cause of the issue.