The Last Guardian is releasing soon and Digital Foundry released an analysis video detailing how the game runs on the PS4 and PS4 Pro. Despite being on stronger hardware after moving from PS3 too PS4, the game still has some major frame rate issues on base PS4, with it going from 20-30 FPS. When it was in development on the PS3, the game ran at 10FPS from released footage, so all the different effects and AI work the game offers likely is a hardware strain.
But PS4 Pro has two modes (both you need to access from the PS4 OS Level Menus); 1080P and 4K. The former offers an almost locked 30FPS while the later is better running than base PS4 and has sharper image quality.