Bummer performance is a problem for ya. We've worked on it a ton over the past year or two and generally performance should be much better across the board. Feel free to email me (username @ makenotion.com) if you have example pages that are slow you're willing to share. thanks!
your OS shows a microphone icon when apps are recording audio — when you use the app, you should see that when recording is on during the meeting transcription and off otherwise
2. Notion desktop app has notifications about meetings that ask you if you want to use Meeting Notes, it recognizes this by detecting that your microphone is on (i.e. it does not listen to audio coming from your microphone). This feature is a setting in preferences btw, under Notifications > Desktop meeting detection notification.