In the recent Xbox Insider builds, Microsoft has improved the boot times of both Xbox Series X|S and Xbox One consoles.
In the case of Xbox Series X|S, Microsoft created a shorter boot up animation (~4s) from the original boot up animation (~9s), to reduce the overall startup time.
According to Jake Rosenberg, Senior Product Manager Lead at Xbox, Xbox One generation consoles are booting noticeably faster with these changes.
If you are a Xbox Insider, did you notice improved boot times in your console after the recent update?