Persistent only means each object writes its x/y/z coordinates into a “text file”, bloating up the save file. That’s nothing really computationally heavy lifting. If you then have to render that stuff it’s the same load on the cpu / gpu as rendering a 500.000 poly model or loading the stack of barrels in crysis.
Or am I missing something here?
It's absolutely NOT just a text file, let me give you and example of how it works.
You, the player, go into Crassius Curio's mansion and steal his signed "Lusty Argonian Maid Premium Edition" from him. You bring it to your home and put it near your bed on top of a table next to a bowl of apples. You go out on your adventures for an in-game week and save the game. Next time you open the game, you decide to first drop all your loot in your house first. You enter your house and go upstairs to your bed. You know notice that the book you stole is gone and there is a note there. You read the note and it says "Next time you steal from me will be your last. Signed, Curio. PS: Me and my boys ate all your apples as well get f***ed".
Now let's see what happens behind the scenes between you enter your house and see the book stolen and apples eaten.
Papyrus Virtual Machine (Scripting language for all Bethesda games in the last decade) starts to check things:
-Game checks whether Curio's book is still in your house after a week
-When it confirms it is , it RNGs whether thieves hired by Curio will enter your house and steal back that book.
Let's say game decided that Curio sends his thugs.
HERE IS THE IMPORTANT PART FOR THE TOPIC:
- Game checks the location of said book.
- Thief NPCs break into your house and come upstairs (You can catch and kill them btw if you wait in your house (this isn't one of the examples of quest stage going from 110 to 120 and script updating to tell you your book has been stolen btw, BGS uses those type of questing scripts as well) but we'll assume you were away)
- Game despawns the book from your house and respawns in Curio's house with the exact coordiates it calculated to be it's "proper place" aka where you stole it in the first place.
- Game also checks whether the table that holds both the bowl of apples and the book has any other items
(For our case it finds the apples and runs the script that deletes those apples aka "We ate them" could be any other scenario)
- Game spawns the note at the exact coordinate where book used to be and it knows which way is up on the table so it does not look upside down when you bring your crosshair on it to take it.
- Thieves go out of your house and follow the path to Curio's house.
Are you getting my point now? It is not just a text file , this is part of a radiant quest and game NEEDS TO KNOW ALL THESE THINGS TO RUN THAT QUEST PROPERLY.
Does it ? Only sometimes, there is a reason the term "Bugthesda" exists.
Does Bethesda use this part of their engine enough?
ABSOLUTELY NOT. In fact, Obsidian, at times, used this part of the engine better than Bethesda used in their games.
I hope this demonstrated what i mean by persistence to you.
