World Partition, how to permanently destroy an actor at runtime ?

Performance is probably irrelevant here.
When things are a core mechanic you don’t give a toss about what the cost is.
Within reason ofc, you know. You shouldn’t waste 30 seconds on loading a single asset for instance.

Still, people will put up with it if you do it as a Loading option.

Best example I can give is dynamically editing Foliage, manually saving it, and re-loading it any time you reload the level.

Its expensive. It’s intense (billions of instances to store/read/write), but just about every game does if one way or another…