Recent builds of Windows 10 preview have started notifying that you have apps in the startup page of settings. Ironically, one of the culprits it may be fingering is Cortana, which as it migrates toward obsolesce, has been moved to a Windows App that starts from the startup settings page.
It’s unclear to me if this is just letting people know that the setting page is there so they can refine decisions made on their behalf as apps were installed, or if they are particularly concerned about startup speed. One thing I really wish Microsoft would do is change these messages from “We’ve noticed” to something more clearly directed at Windows “Windows has noticed” or maybe something less anthropomorphic like “There are some apps registered to start when you log in”.