What is Windows Fast Startup and when to use it?

If your Windows PC takes a while to boot up, you may have come across a setting called Windows Fast Startup. This feature is designed to help your computer start faster after shutdown, but it’s not always the best option for every user. Understanding what Windows Startup (Fastboot) is and how it works can help you decide when to use it and when to turn it off.

What is Windows Fast Startup?

Windows Fast Startup (also known as Fastboot or Hybrid Boot) is a power feature in Windows 10 and Windows 11 that helps your PC start faster after shutdown. It works as a middle ground between a full shutdown and hibernation, combining the benefits of both.

Instead of completely closing the operating system, Fast Startup saves the system kernel and active drivers to a file called hiberfil.sys during shutdown. When you power the computer back on, Windows reloads this saved kernel state into memory rather than initializing everything from the beginning. This reduces startup time by skipping many low-level system initialization steps.

Windows Fast Startup was introduced with Windows 8 in 2012 and continues to be available in Windows 10 and Windows 11, where it is enabled by default on most systems.

How does fast startup work?

Windows Fast Startup uses a hybrid shutdown process that removes user activity while preserving the core operating system state. This allows Windows to start faster without resuming your previous session.

What happens during a Fast Startup shutdown?

When you select Shut Down with Fast Startup enabled, Windows follows these steps:

1. User logoff: Windows closes all running applications and logs you out of your user account. This ensures a clean user session on the next boot.

2. Kernel hibernation: Instead of fully shutting down the operating system, Windows places the system kernel and active drivers into a hibernation state.

3. Writing system state to disk: The kernel and driver data are compressed and saved to a file called hiberfil.sys, located on the system drive (usually C:).

4. Power down: The system then powers off completely.

The role of a quick resume

When you power the PC back on, Windows performs a quick resume instead of a full boot. The boot loader reads the saved kernel data directly from hiberfil.sys into memory, skipping many hardware and driver initialization steps. This streamlined process can reduce startup time by up to 50% compared to a traditional cold boot.

When to use Windows fast startup, and when not to?

Windows Fast Startup can significantly reduce boot time, especially on older systems. However, there are scenarios where enabling it may cause issues. Knowing when to use or avoid this feature helps you get the best experience.

When is Fast Startup beneficial?

• HDD users: If your system runs on a mechanical hard drive (HDD), Fast Startup is highly recommended. Loading a compressed hibernation file is much faster than initializing Windows from a spinning disk.

• Older hardware: PCs with slower processors or limited resources benefit from skipping full hardware initialization, resulting in noticeably quicker startups.

When is Fast Startup problematic?

• Dual-boot systems: If you use Windows alongside Linux or another operating system, Fast Startup locks the Windows partition to protect hibernated data. This can prevent the other OS from accessing files and may lead to data corruption.

• System maintenance and troubleshooting: Since the kernel doesn’t fully shut down, system uptime doesn’t reset after shutdown. This can make troubleshootingdriver or performance issues more difficult.

• Windows updates: Some updates require a full shutdown and restart. Fast Startup may delay or block these updates unless you manually choose Restart.

• Accessing BIOS/UEFI settings: With Fast Startup enabled, the boot process can be so quick that pressing keys like F2 or Delete to enter BIOS/UEFI becomes difficult.

Fast Startup vs. Full Shutdown vs. Hibernation: Key differences

The primary difference is that Fast Startup saves the system kernel but discards the user session, whereas Hibernation saves both, and a Full Shutdown saves nothing.

What are the pros and cons of using Windows Fast Startup?

The biggest advantage of Windows Fast Startup is faster boot times, while its main limitation is that it does not perform a full system refresh during shutdown.

Pros

• Speed: Drastically reduces wait times when powering on the PC, especially on legacy hardware.

• Convenience: It is enabled by default, requiring no configuration from the user to see benefits.

• Efficiency: Uses the hibernation file intelligently, requiring less space than full hibernation because user data is excluded.

Cons

• Interference with Encrypted Images: Users of encryption software like TrueCrypt or Veracrypt may experience issues where encrypted drives remain mounted or cause file system errors.

• Hardware Changes: If you perform hardware upgrades (like swapping RAM or a drive) while the PC is "shut down" with fast startup, the OS may not detect the change upon booting because it reloads an old hardware configuration from the disk.

• Locked Drives: As mentioned regarding dual-booting, the file system is placed in a "read-only" or locked state, which can be problematic for external tools trying to access the Windows drive.

Should you disable Fast Startup on your PC?

Whether to disable Fast Startup depends on your usage and system setup. You may consider turning it off if you:

• Dual boot with another OS: Fast Startup can lock the Windows drive, causing file access issues for Linux or other operating systems.

• Frequently perform hardware changes: Windows may not detect new hardware immediately if the system state is loaded from the hibernation file.

• Experience update or driver issues: Some updates require a full shutdown to apply properly; Fast Startup can interfere with installation.

• Need consistent BIOS/UEFI access: Fast Startup can make it difficult to enter BIOS during boot due to the faster startup sequence.

However, users relying on mechanical hard drives should keep it enabled. The time saved during boot-up is tangible and improves the day-to-day experience significantly.

How to enable or disable Fast Startup in Windows?

Method 1: Using the Control Panel power options

This is the standard, user-friendly way to enable or disable Fast Startup:

1. Open the Start Menu, type Control Panel, and press Enter.

2. Navigate to System and Security > Power Options.

3. On the left sidebar, click Choose what the power buttons do.

4. Click Change settings that are currently unavailable at the top (administrator privileges may be required).

5. Under Shutdown settings, locate Turn on fast startup (recommended):

   • Check the box to enable Fast Startup

   • Uncheck the box to disable it

6. Click Save changes.

Method 2: Using the Command Prompt or PowerShell

Fast Startup depends on hibernation, so enabling or disabling hibernation also affects Fast Startup.

To disable hibernation (and Fast Startup):

1. Right-click the Start button and select Windows Terminal (Admin), Command Prompt (Admin), or PowerShell (Admin).
2. Type the following command and press Enter: powercfg /h off

To enable hibernation (and Fast Startup):

1. Open the terminal as administrator.

2. Type the following command and press Enter: powercfg /h on

How to perform a full shutdown with Fst Startup enabled?

Even with Fast Startup turned on, you can perform a complete shutdown when necessary:

• Option A: Hold down the Shift key while clicking Shut down in the Start Menu.

• Option B: Use the command line: shutdown /s /t 0

Windows Fast Startup vs. BIOS/UEFI Fast Boot: Clearing the confusion

Windows Fast Startup is an operating system feature, while BIOS/UEFI Fast Boot is a firmware feature handled by your motherboard.

Conclusion

Windows Fast Startup is useful for HDD systems, speeding up boot by combining shutdown and hibernation. On modern NVMe SSDs, the benefits are minimal, while issues like locked drives and uptime errors persist. Disabling it ensures a cleaner, more stable system without much impact on boot time.