Using AI to prep managers before performance reviews. What are you doing?

Well there are different ways to go about this but I honestly don't think this is what Copilot is actually for. Performance reviews and management overall is too complex a process with too much riding on it that trusting a tool not specialized in it isn't worth the effort.

If you really want to harness AI for this process, there are plenty of strong HR/performance review software in the Microsoft app store with very strong AI features. While I am not the biggest AI person, I know for a fact that Teamflect, the tool we currently use for performance reviews, has an AI assistant built in that can analyze performance data, goals, etc, and can help managers and employees prepare for meetings. 

I've heard great things about it internally and have experimented with it myself. I can strongly recommend you give it a try.