In Windows 10, the Fast Startup feature (also known as hiberboot, hybrid boot or hybrid shutdown) is a combination of the shutdown and hibernation features. When the mode is enabled, your computer will start faster after shutting it down. Windows 10 achieves this by saving drivers and system related files to a hibernation file when you shutdown your computer.
When your switch your computer on, Windows 10 resumes from hibernate rather than starting up from scratch.How to enable the hibernate feature in Windows 10
As Windows 10 resumes from hibernate, you need to ensure the feature is enabled or else it will not be possible to enable Fast Startup.
If, for some reason, you do not have the hibernate feature enabled, follow the below steps:
Right click the Start button > click Command Prompt (Admin) > type powercfg –h > press Enter.
Step 1: Click the Start button > select Settings. In the Settings menu > click System > Power & sleep > Additional power settings.
Tip: If Turn on fast startup (recommended) is greyed out, then click on Change settings that are currently unavailable. A User Account Control (UAC) pop-up window, may prompt you to confirm your choice > click Yes. The Fast Startup option should now be available for selection.
Step 5: Shutdown your computer and switch it back on again to see what effect the enabled feature has on your startup time.