1. Performance management is never easy and I don't think it should be. I don't mean the technique or process of it bit the mental weighing of it. You are affecting a person's livelihood so you don't want to approach it robotically always (despite what the hr training tells you about it not being personal etc)
2. This is a big one. Performance has a huge under rated aspect that is environmental and circumstantial. I've seen really strong performers drop and fail because of personal situations and not being able (or rather not given the space and bandwidth to recover organically). And similarly those with a poor perf in one company go to a supposedly "higher tier" company and really thrive and sky rocket.
Management is really a mixed bag. I loved the coaching, direction setting, strategy, etc but always having to sell opaque higher up decisions as your own and being an inverted $hit umbrella for leadership can be draining. I guess the solution is to just join executive leadership ha.