Unfortunately, it seems Uncharted 4: A Thief’s End‘s single player mode will only have a max frame rate of 30 FPS. During a Q&A session with the developers, co-lead designer Anthony Newman said,
We had a really long, involved conversation about it with all the leads and directors. We just realized that, for the game we wanted to make, to make the best game possible, [30 FPS] was just something that we had to do.
Without capping the frame rate at 30 fps, the game’s development time would have been extended significantly. Thankfully, the game’s multiplayer mode will run at a smooth 60 FPS.