It's well known that adding/removing components is a slow operation in archetype-based ECS systems. One solution that Unity is working on for their ECS (also archetype-based) is using bit flipping to enable/disable components quickly at runtime.

Here's the CTO of Unity describing their approach:
https://forum.unity.com/threads/dots-skill-system-repo-available.894007/#post-5875804

I imagine something like this could be useful for Bevy.