The Xbox One S is all set to bring 4K video streaming and HDR in a chassis that's 40% smaller than the Xbox One. While Microsoft didn't go into a lot of detail regarding the hardware powering the console, it looks like the Xbox One S will feature upgraded internals that will result in better framerates.
According to Polygon:
The Coalition studio head Rod Fergusson talks in particular about improved surface detail on things like metal and armor — it will also provide a more consistent level of technical performance as well, Fergusson told Polygon in an interview following Microsoft's press briefing today.
According to Fergusson, the Xbox One S has additional raw GPU and CPU power compared to the Xbox One, and The Coalition's engineers have been able to take advantage of that to reduce the frequency of frame rate or resolution penalties in more demanding sections of the game.
The Xbox One S will make its debut in August, and is up for pre-order right now.
Update: In a statement to The Verge, Microsoft confirmed there are additional resources available to developers, but it looks like it only applies to HDR games. Which makes sense.
We have the same SOC architecture as Xbox One today. For games that want to take advantage of HDR, we gave developers access to a small amount of additional processing power.
So there we have it.