The PS4 processor isn't limiting it at all, otherwise every game on the system would be suffering from this and Sony's social media accounts would be crippled by raging users. The fact that it's also taking 25mins+ on PS4 Pro, means it has to have something to do with the actual install of the files or utterly atrocious coding. To put it into perspective; a clean install of FFXV is quicker downloading and applying it's monstrously huge patches.