Apple does not support or fix third party apps.

This is 100% chrome, with their annoying updating agent, which you can't remove

You're awfully confident for someone who has provided no additional evidence.

The OP claims the high CPU usage went after uninstalling chrome and rebooting their machine.

Rebooting their machine.

The thing we tell everyone to as the absolute first step in trying to solve any problem with a computer, "have you tried turning it off and on again?".

This isn't proof that chrome or keystone or anything at all caused the problem. We have nothing to determine the root cause.

I've had numerous problems with keyagent. It was horrible. I spend way too much time on trying to get that monster to work normally or get it removed.

But it's an "essential part" of chrome

Apple likes it when the products they sell work properly and would like to hear about it when common third party products are causing that to not happen.

Yeah, next time I'll try that as well! Completely forgot Feedback Assistant existed, but I'm glad it is back to normal speeds now.