Not the person you replied to but auto discard only helps so much. Even with it on I often use 80-90% memory (albeit on Windows, not sure if macOS is any different in this regard).
Firefox here too, no such problems. I do however run Google services in a separate browser (Brave or Chromium) because most of them hog the Firefox browser. For example running earth.google.com on FF is... a very special experience. :-/
