https://www.youtube.com/watch?v=0eBaPS3uj-A
"Demo uses backward compatible Xbox title to demonstrate load time technology and does not represent gameplay optimized for Xbox Series X.
Through Xbox Series X's revolutionary Velocity Engine Architecture, gamers will experience more time playing and less time waiting as loading times will be greatly decreased and fast travel systems will be just that: fast."
PS: no word on whether or not the XBONE being compared here had SSD or normal HDD.