Fast Startup (also known as Hybrid Boot) is a new feature introduced first with Windows 8 to start a computer faster than the time required to start a PC with the traditional cold startup. Fast Startup is present in the latest Windows 10 as well and is turned on by default.
How Fast startup works?
According to Microsoft, when you shut down your Windows 10 PC, after closing all running applications, Windows automatically saves the copy of loaded drivers and kernel to a file called hibernate file (hiberfil.sys) located in the root of the drive where Windows 10 is installed.
As you likely know, the hiberfil.sys is usually used by the hibernation feature, but when you send the shutdown signal to a PC where Fast startup is turned on, the hiberfil.sys file will be used to save loaded drivers and kernel before shutting down, so that Windows can quickly load them back into memory when you turn on your PC.
Because Windows saves loaded drivers and kernel to hiberfil.sys file, which is otherwise used by the hibernation feature, to enable Fast startup feature, the hibernate feature must be turned on. For those who are not aware, Windows creates hiberfil.sys only when the hibernation feature is turned on.
So please make sure that the Hibernation feature is enabled on your PC before proceeding further. Refer to how to enable or disable the hibernate feature in Windows 10/8 guide for detailed instructions.
By default, Fast startup is turned on, and Windows uses the same instead of cold startup (traditional startup). But if you have a feeling that your PC starts slowly after shut down, checking the status of Fast startup is a good idea.
Turn on or off Fast startup in Windows 10
Tip: If you have turned on Fast startup but want to perform a traditional cold shut down once in a while without turning off Fast startup or hybrid boot, open Command Prompt as administrator, type shutdown /s /f /t 0, and then press Enter key.
Step 1: Open the Control Panel, change the View by to Small icons and then click Power Options to open the Power Options window.
Step 2: In the left pane of the Power Options window, click the link labeled Choose what the power buttons do to open the System Settings window.
Step 3: Here, click the link named Change settings that are currently available.
Step 4: Scroll down, under Shutdown settings section, check the box labeled Turn on fast startup (recommended) to enable fast startup feature. Unchecking the Turn on fast startup box will turn off the feature. Once you select or deselect, click the Save changes button.
And if Turn on fast startup option is not appearing, as said at the beginning of this article, it’s likely because the hibernation feature is turned off on your PC. You need to enable the hibernation first, and then follow these steps again to see Turn on fast startup option.
If the hibernation is turned on, you must see the Hibernate option under Shutdown settings just above Sleep and Lock options.
Turn on or off Fast startup using Registry
Step 1: Open Registry Editor by typing Regedit in the Start menu or taskbar search box, and then pressing Enter key.
Step 2: Once Registry Editor is launched, navigate to the following key:
Step 3: On the right side, locate the value named HiberbootEnabled, double-click on it, and change the value data to 1 (one) to turn on the fast startup. Set the value to 0 (zero) to turn off the feature.
Hope this helps!