TheUser1 JChips
Just to clarify, what Safari does is same from resource consumption standpoint
https://eclecticlight.co/2021/11/12/how-safaris-tab-groups-consume-memory/
the difference is that the user doesn't see it, so they assume they are not using memory.
Now where the difference currently exist is that Safari will also sync tabs to iCloud so they persist while we are working on this right now (together with bookmarks sync).
So lets separate persistence from the implementation of tab grouping. We used windows because that is what windows naturally do - hold a group of tabs so we get this "for free". Safari introduces one more level of abstraction, having group of tabs inside a group of tabs (window), which has no resource use benefit but has a software complexity penalty. We like keeping Orion as lightweight as possible.