not sure you’re on the same page. Dynamically adding level with baked in navigation is not the same as putting navigation in sublevels that are referenced by the persistent level. That would cause bloat.
In my case, I’m using dungeon architect to spawn level instances that have their nav mesh baked. I have no performance issues with this and I’m doing it on an oculus quest which has far less power than the ps4. I think you need to validate your set up as likely what is happening is your navmesh is being regenerated.
I’ll do a quick blog post or something about how to set this up properly at some point.