Not sure who it was a few days back asking if anyone else had slow menus after the most recent Xbox One update, but yeah, my system is completely borked. With the new dashboard, starting up games takes forever now and they fail to launch more often, just returning to the home screen with no message. Sometimes hitting the home button just dims the screen for 15-25 seconds before the menu finally pops up. I'll get a gray screen for about 20 seconds when clicking on my download queue. Everything just seems sluggish now.
Ok, I've had that exact same issue now myself as well. I honestly thought it was because the extra load on XBL with everybody being quarantined and all. Whatever online check-ins on the dash are being delayed by a few seconds. At least that's my baseless theory.