My Fenix doesn't do it every ride, or if it does I miss the notification sometimes.
Performance condition is a data field, you can add it to a screen and see it in real time. Garmin says the purpose is that the number should fall off a cliff before you bonk, so you can avoid the pain by limping home when it starts to drop. You already know the watch is calculating so that won't really narrow anything down, but it'll make the data available when you want it. (Still takes 10+ minutes to get a read though.)