What is Windows Fast Startup? Do you have to turn it off


Windows Fast Startup is kernel-only hibernation that dramatically reduces boot time the next time you start your computer. It is also known as hybrid stop. This feature was introduced with Windows 8 and has now become one of the key features of the Windows operating system.

If you haven’t heard of Fast Startup, it’s probably because the feature comes pre-enabled with your Windows installation, requiring no user action to interact with it. That is, unless you want to turn it off.

So what benefits do you get from a quick start? Is there a scenario where you might want to disable it? We have answers to these questions in the article below. Please read and enjoy!

What is Windows Fast Startup?

Fast Boot is one of three boot modes in the Windows operating system. It was introduced with Windows 8 in 2016.

The three Windows boot modes are:

  • cold start,
  • Waking up from hibernation and
  • Quick Start.

Cold start

If your machine is configured for a cold startwhen you run shutdown, the operating system safely terminates running threads, closes user sessions, unloads drivers and kernel from memory, and finally shuts down.

The next time you start your PC, the operating system’s boot loader builds a kernel image by reading from the hard drive and loading it into memory. The kernel then configures core system functions and loads essential drivers into memory.


Hibernate is a Windows feature that basically emulates sleep mode on shutdown.

Sleep mode is a Windows power saving feature that freezes the current state of the device by saving loaded applications, drivers, and kernel to memory while suspending activities. This allows the device to engage in a very low power mode, which is useful if the user wants to take a short break from working on their computer.

Hibernate essentially performs the same function. However, instead of saving the state of open applications, drivers (kernel mode and user mode), and the kernel in memory, which is volatile, it instead stores those states on the hard drive in hyberfile.sys. Thus, the operating system is able to shut down completely.

On the next boot, the saved states of hyberfile.sys are read and loaded into memory, allowing the user to quickly pick up where they left off.

Quick Start

Fast start combines the ideas of cold start with hibernation to provide hybrid shutdown. When fast boot is enabled, kernel state and loaded kernel-mode drivers are written to hyberfile.sys when you issue a stop command. Open applications and user-mode drivers are exempt from being written in hyberfile.sys.

The next time you start your device, the saved state stored in hyberfile.sys is loaded into memory by bypassing the initialization phases of a cold start. As a result, a significantly faster start time is achieved compared to a cold start.

One caveat that users should be aware of is that hibernation must be enabled to enable fast booting. You cannot disable hibernate and enable fast startup in Windows.

Benefits of Quick Start

Since Fast Startup is enabled by default, many users may not be aware of the benefits it offers.

  1. Quick start time: As the name suggests, the main advantage of fast boot is a significantly reduced boot time. Cold booting your computer can take anywhere from 20-30 seconds to over a minute. Quickstart typically reduces this time to less than 10 seconds.
  1. System performance: Since kernel and kernel mode drivers are already initialized when loaded into system memory, overall system performance should be significantly improved.

Disadvantages of Quick Start

Due to the speed with which boot is implemented, there are also some significant downsides to enabling it in your system.

  1. Storage space: Quick start uses hyberfile.sys file on hard disk to save kernel state before shutdown. The size of hyberfile.sys usually accounts for about half of the total system memory. This is a dedicated storage space that you need to allocate in the main partition of your hard disk to be able to use fast startup. For people who use a small SSD (128 GB or less) to load their operating system, this can be a problem.
  2. Dual Boot: If fast startup is enabled, Windows locks the hard drive partition where Windows is installed. This partition will be inaccessible from another operating system if you have configured dual boot on your system.
  3. Access BIOS/UEFI: When fast boot is enabled on some systems, you may not be able to access BIOS/UEFI when booting from a shutdown state. On such systems, you will need to restart your computer to access your BIOS or UEFI.
  4. Problem with encrypted disk images: Some users have reported fast boot features interfering with mounting and unmounting encrypted disk images. For example, TrueCrypt users have reported that their encrypted disk images remain mounted after system shutdown, which is a security issue.

Should fast startup be disabled?

If you’re a regular user, you’ll likely benefit more from the improved boot times it brings to the table than any other downsides it presents. As such, disabling fast startup is not recommended for the vast majority of users.

However, as we have already seen in the disadvantages section above, there are specific scenarios in which you can disable fast startup.

Users likely to need fast boot are those who need dual boot enabled in their system. You can also disable Fast Boot to access BIOS or UEFI if your system prevents access.

Finally, if you are having problems with mounting/unmounting or automatically mounting encrypted disk images, it is advisable to disable fast boot.

How to disable fast startup

If you need to disable fast startup, please follow the steps given below.

  1. Press Win + R and type control to launch the Control Panel.
  2. Move towards System and security > Power Options.
  3. Select Choose what the power buttons do.
  4. Click on Change currently unavailable settings.
    Modify the parameters
  5. Uncheck Enable fast startup (recommended).
    Disable fast startup

Frequently asked question

Can you get started quickly with Hibernate disabled?

Hibernate consumes a significant amount of disk space, so it’s understandable that you want to disable this feature while maintaining fast startup. You can do this by switching from full hibernation to reduced hibernation.

To enable reduced hibernation, please follow the steps below:

  1. Press Win + R, type cmdthen press Ctrl + Shift + Enter to launch the elevated command prompt.
  2. At the prompt, run the following command: powercfg /h /type reducedReduced hibernation

If you have compressed your hibernate file to save disk space, running the above command will throw an error. In this case, you will first need to unzip the hibernate.

  1. In the elevated command prompt, run the command: powercfg hibernate size 0
  2. Then run: powercfg /h /type reduced

Is fast boot the same as hibernation?

Fastboot is similar to hibernation, but differs in one critical aspect.

Windows hibernation saves the state of everything including open applications, user sessions, user-mode drivers, kernel-mode drivers, and the Windows kernel in hyberfile.sys. On the next startup, the save state is reloaded into memory, allowing you to pick up where you left off before stopping.

In contrast, Fast Boot only logs the states of kernel-mode drivers and the Windows kernel in hyberfile.sys. This allows for faster Windows initialization and loading time. Any applications or user sessions that were open before the shutdown are not recovered.


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