I thought there were some games that had slightly more stable framerates on the XBO and the CPU was suggested as the reason?
Clearly the GPU isn't a bottleneck for either version of the game, so if it is performing worse on the PS4, I can't imagine what the reason would be other than the CPU.
And again this is just assuming it's not a bug that Bethesda can't just fix. Because it's not like it looks like there is particularly anything intensive going on in the scene.
The reason is Bethesda.