When you hover the mouse pointer on your score, you can read the following:
Your startup system needs optimization, it has a health score of ... out of 100. You can improve the rating by enabling the Startup Optimizer and disabling any unneeded startup software with the Start Manager.
Startup Optimizer = Home (Main screen) > Speed up my computer's startup > enable (see Handook, p. 46-47).
Startup Manager = Home (Main screen) > Control which programs start automatically (see the Handbook p. 48-49).
Be cautious with enabling Startup Optimzer. You must know what you are doing (read the Handbook p. 46-47).