https://www.gamespot.com/articles/xbox-one-july-update-introduces-faststart-and-grou/1100-6460191/

Microsoft has begun rolling out its July Xbox One update, which includes a few key features that the company has promised lately. The headliners are FastStart, which was announced at Xbox's E3 media showcase, and Groups, which was tested for Alpha users last month.

FastStart uses machine learning to identify which files are needed first and prioritize those downloads so you can jump into a game faster while the rest of the file finishes. Microsoft boasts this means you can start up a game twice as fast. For the time being, this is limited to a select number of titles. But while it was presented in the context of Xbox Game Pass, today's update appears to make the feature available for everyone.