As a result, at a bare minimum, Xbox Series consoles should retain three to four "next-gen" game save states for the sake of Xbox Quick Resume—though, thanks to my back-compat limits, I've been unable to test this claim as of press time.
Instead, I've pushed my tester Xbox Series X console with a mix of XB1, X360, and OGX content to test how many save states I can cram into the console's internal memory before the feature stops working. My average result has been 12 games. Meaning, I can manually load 12 games, then go back in order to reload each of the dozen, and they'll each have a brief "Quick Resume" tag appear on the screen before reappearing in fully playable, middle-of-the-game action within five to 12 seconds.
Xbox Series X hands-on: The big back-compat dive begins [Updated]
Xbox Quick Resume impresses. Plus: New controller, auto-HDR, venting holes, and more.
arstechnica.com
Really nice feature, this.