When Microsoft announce the new n Xbox One S at E3 2016, they indicated that the console’s performance will remain the same but it looks like Microsoft might have been downplaying their Xbox One S.
According to Digital Foundry, the new Xbox One S performance has been upgraded. They measure a 7% GPU jump from 853MHz to 914MHz along with an ESRAM bandwidth jump from 218GB/s to 204GB/s. The difference is not that big which could explain why Microsoft did not even bother to mention them but an improvement is still an improvement.
Digital Foundry also added that games have a more consistent framerates on the new Xbox One S and that backward compatible games run smoother on the new console.
The difference is not big enough to convince the original users to make the upgrade but it is still good news for those looking to buy the new Xbox One S.