Since Windows Vista, Microsoft has been trying to improve Windows startup after you log on so that startup programs don't open all at once when the system is still loading its processes. Windows Vista had a "Startup Delay" feature. In Windows 10, when the OS is started, it delays the loading of apps from the Startup folder, especially when the Start screen is enabled. This behavior was implemented by Microsoft in Windows 8 as it was a tablet-oriented OS. You can reduce this startup delay for desktop apps with a simple Registry tweak.
In case you aren't aware of this, Windows 8 delays the startup for all desktop apps. Shortcuts located in your Start Menu's Startup folder as well as the items which run from various Registry locations will be launched after a delay of few seconds. This behavior was implemented by Microsoft probably because Windows 8 is a tablet-oriented OS (another example of how the Desktop takes a backseat in Windows 8). However, you can reduce this startup delay for desktop apps by editing the Registry. Read this post to learn how.