On existing and past generations, texture/LOD pop-in was caused by slow I/O, you'd need to be pulling data for where the character would be in 10-20 seconds, which could be a lot of places in an open world game because they could go in any direction - so the slow I/O problem is compounded by also pulling data for a lot of places that character will not be (but might have) which increase memory usage. On nextgen, this will be much less of an issue because you can pull data much later, meaning very little speculative I/O. This is an I/O and memory win not just in the orders of magnitude for fast I/O, but in the amount of needless I/O saved and memory used.