Advanced guide to optimizing the Windows kernel and performance

Informatec Digital » Resources » Advanced guide to optimizing the Windows kernel and performance

If your Windows PC boots slowly, moves files like it's carrying heavy weight, and games or programs freeze for no apparent reason, there's likely room to improve the kernel and optimize services and performance . You don't need to be a Microsoft engineer to notice that, over time, the system becomes cluttered with inefficient processes, services, and configurations that strain the CPU, RAM, and disk.

Although Windows comes fairly well optimized out of the box, there's a combination of "official" settings, advanced tricks, and good maintenance practices that allow you to significantly improve kernel, I/O, and network performance . From how the Windows kernel boots (fast startup, hibernation, power modes) to how it uses memory to cache files and communicate with your SSD, almost everything can be tweaked… as long as you know where to tweak it and what the risks are.

What is the Windows kernel and why does it have such a significant impact on performance?

The Windows kernel is the system's "conductor": it manages the CPU, memory, disks, network, and drivers . Every time you open a program, move a file, or browse the internet, the kernel coordinates all those operations in the background.

When the kernel or its configuration is not properly adjusted for your hardware or your usage patterns, problems begin: disk I/O bottlenecks, high latencies, random crashes , high CPU usage for no clear reason, or a feeling that the computer is "stuttering" even in simple tasks.

Some of the most powerful optimizations don't involve installing miracle programs, but rather changing how Windows organizes its cache, how the kernel boots, how it manages power states, and how it allocates RAM for the file system . These are changes that act directly at the kernel's operating layer.

Windows Fast Startup: How it speeds up boot times and when to disable it

Fast Startup (also known as hybrid boot) is a feature in Windows 10 and 11 designed to drastically reduce the time it takes for the system to boot . At first glance, it looks like a normal shutdown, but internally it does something very different.

When you shut down with fast startup enabled, Windows closes your programs and your session, but it doesn't completely shut down the kernel or the drivers : it saves that state in the hibernation file (hiberfil.sys) and then, when you turn it on, it simply reloads it instead of starting from scratch.

With this technique, the system avoids much of the slow hardware and driver initialization. On computers with mechanical hard drives, boot times can be reduced from 30-90 seconds to around 10-20 seconds ; on SSDs, the gain is smaller, but it still represents a difference of a few seconds that makes a noticeable difference in everyday use.

The key is to understand that this mode is an intermediate point between shutting down and hibernating: it doesn't keep your applications open like classic hibernation , but it also doesn't perform a completely clean shutdown like restarting.

Differences between fast start, full shutdown, sleep, and hibernation

Windows handles several power states, and each one implies a different behavior of the kernel and hardware:

• Quick startThis closes the user session but saves the kernel and drivers in hiberfil.sys. On the next boot, it reloads them directly, shortening the boot time.
• complete shutdownClose everything, clear the RAM, and completely shut down the system. The next startup will be a cold boot, slower but completely clean.
• HibernationSave the entire contents of RAM (kernel, drivers, and your open programs) to hiberfil.sys and shut down your computer. When you return, resume your session exactly as you were.
• SuspensionThis keeps the powered RAM in a low-power state. The PC "wakes up" almost instantly, but still uses some power.

In terms of performance, fast startup is useful for everyday boot times on computers that are frequently shut down , while classic restart is the safer option when you're installing Windows updates or changing hardware.

Advantages of quick start in daily use

Enabling (or keeping enabled) fast startup has several practical advantages, especially if your PC boots from an HDD:

• It significantly reduces startup timeespecially on mechanical hard drives, where the seconds you save make a much bigger difference.
• It makes the shutdown seem normal: The equipment shuts down, the fans stop, and there is no power consumption., unlike suspension.
• It saves more energy than leaving the PC in sleep mode.because the hardware is completely powered down.
• It works transparently on both BIOS and UEFI systems, without requiring special hardware.

For the vast majority of home computers with Windows as the only operating system, maintaining fast startup is usually a good way to make Windows boot more responsive without overcomplicating things.

When should you disable fast startup?

It's not all advantages. There are certain scenarios where a quick start can be more of a hindrance than a help, and it's best to disable it:

• Dual-boot systems (Windows + Linux or other systems)When hibernating the kernel, Windows leaves the partition in a "locked" state and other systems should not mount it, risking corruption.
• Need for Wake-on-LAN or remote managementIn hybrid shutdown, the machine is technically hibernated, which may prevent the network card from accepting remote power-on packets.
• Problems with Windows updatesSome patches require a true cold boot. With fast boot enabled, the kernel can get stuck in an intermediate state, causing endless "Setting up Windows..." loops.
• Difficulty entering BIOS/UEFI: by not doing a complete POST, sometimes it is almost impossible to catch the moment to press the corresponding key.
• Computers with limited disk spaceThe hiberfil.sys file can easily take up 70-75% of your RAM, which is a real pain on small SSDs.
• Conflicting hardware or driversVery old equipment or equipment with unusual controllers may behave poorly when resuming from a hybrid shutdown.
• Critical servers and workstationsIn these environments, a completely clean reboot of the kernel and hardware is prioritized.

In any case, if you're installing a major update or struggling with stability issues, it's good practice to use the Restart option instead of Shut Down , as restarting never uses fast startup.

How to enable, reduce, or disable fast startup in Windows 10 and 11

If you want to check the status of fast startup or adjust it to your liking, you can do so from the classic power settings:

• Open the Control Panel → System and Security → Power Options.
• In the sidebar, tap “Choose the behavior of the power buttons”.
• Click on “Change settings that are currently unavailable” to unlock the shutdown options.
• At the bottom, check or uncheck “Turn on fast startup (recommended)”, and save the changes.

If the checkbox doesn't appear at all, hibernation is most likely disabled. To re-enable it, simply open an administrator console (Command Prompt or PowerShell) and run `powercfg -h on` . The fast startup option should then appear without issue.

Additionally, you can save some disk space by reducing the size of the hibernation file with the command `powercfg /h /type reduced` , which maintains the functions necessary for fast startup but reduces the size of hiberfil.sys.

Power modes, high performance, and the hidden “maximum mode”

Another powerful lever for influencing kernel behavior is the power plan you select. Many systems come from the factory in balanced mode, which prioritizes battery life and lower fan noise over raw power.

When running demanding games, rendering, or very resource-intensive applications, this conservative approach can become a bottleneck: the processor throttles too quickly, disks go into sleep mode, and certain power-saving mechanisms increase latency. If you're looking to optimize gaming performance, see how to optimize Windows 11 for gaming.

High-performance plans, and especially the "Ultimate Performance" mode, force the kernel to treat power in a much less restrictive way, reducing power transitions and aiming to keep the hardware "awake" and at full capacity for longer.

With these advanced plans, the CPU maintains 100% performance, the disks do not go to sleep, hibernation is disabled, and certain internal timers are shortened , which can improve system response under heavy loads at the cost of increased power consumption and heat.

How to activate the hidden "Maximum Performance" plan

In Windows 10 and 11, the maximum performance power plan is usually hidden. To activate it, you need to use the command prompt:

• Open the Run window with Windows + R, writes cmd and press Enter.
• In the console, run:
  powercfg -duplicatescheme e9a42b02-d5df-448d-aa00-03f14749eb61
• Now go into Control Panel → System and Security → Power Options and select the plan “Maximum performance”.

From that point on, the kernel will stop applying certain aggressive power-saving policies. You'll notice that the computer reacts faster to demanding tasks, although in return, power consumption, fan noise, and temperatures will increase , especially on laptops.

Optimize disk I/O and kernel file cache

On many PCs with SSDs, the real bottleneck isn't the drive itself, but how Windows manages input/output (I/O) between the CPU, RAM, and storage . If the file cache is too small or poorly configured, the system is forced to constantly read from and write to disk instead of utilizing memory. There are also techniques to speed up file copying and improve I/O.

There's an advanced kernel setting, accessible with the fsutil tool, that lets you tell Windows how much to "stretch" the memory allocated to the file system cache and the NTFS MFT. This is precisely the option that a well-known tech commentator popularized when he claimed that "your SSD is performing like a ten-year-old drive because of Windows."

How the fsutil behavior set memoryusage setting works

By default, Windows takes a conservative approach: it prioritizes ensuring that applications always have free RAM before allowing the file subsystem to keep more memory for caching data.

The memoryusage parameter , which is configured with fsutil, modifies this internal kernel balance:

• fsutil behavior set memoryusage 2: Enables an extended usage mode, increasing the paged pool limit and allowing the file cache and MFT to reserve more RAM.
• fsutil behavior set memoryusage 1: returns the behavior to its standard mode, which is more prudent with memory consumption.

When mode 2 is activated, the system can improve performance on I/O-intensive tasks , such as frequent transfers of large files, video editing, working with virtual machines or file servers on machines with plenty of available RAM.

However, on modest computers (8-16 GB of RAM) where you have a browser, games, and other applications open, stealing memory from apps to give it to the file system cache can be a double-edged sword: if Windows runs out of free RAM, it will start using the page file , and then what you gain in disk speed you lose elsewhere.

When does it make sense to touch memoryusage and when doesn't it?

This type of tuning was originally designed for professional environments and servers , where the workload is highly predictable and large amounts of memory are available. In that context, giving the kernel more leeway to cache files is almost always a good idea.

On a typical home PC, however, it's best to be cautious. It can be useful if you meet several requirements simultaneously: you have plenty of RAM, you work with large files or intensive I/O, and your usage isn't too variable . On the other hand, if you're short on memory or tend to have many applications open, the benefit will likely be minimal or nonexistent.

Before running commands "blindly" because a video on social media says so, it's worth analyzing your case: look at RAM usage in Task Manager, check if your SSD is actually creating long disk queues , and check if there are other more obvious bottlenecks (antivirus, startup programs, nearly full disk, etc.).

In summary, the fsutil trick can be a plus in specific configurations, but it's far from being a magic button that fixes all performance problems and, if applied incorrectly, can even worsen them.

General system optimization: CPU, RAM, disk, and services

While kernel-level changes are powerful, don't forget the classic Windows tweaks that help everything run more smoothly. Many performance problems stem from systems cluttered with unnecessary services, background programs, and full disks.

Basic maintenance, done correctly, can improve performance by 5% to 40%, depending on the initial state of the computer. The idea isn't to become obsessive, but rather to implement a series of regular routines that free up CPU, memory, and disk space , such as useful scripts for automation.

Update Windows and Drivers

Keeping your system and drivers up to date isn't just a matter of security: many updates include performance improvements and bug fixes that directly affect how the kernel works with the hardware.

To check, go to Start → Settings → Update & Security → Windows Update and click on “Check for updates”. Install the latest available version of Windows and, before restarting, go to “Advanced options” to check for additional drivers (chipset, GPU, etc.).

In many cases Windows Update already takes care of almost everything, but for sensitive components such as chipset, storage controllers or graphics card it may be interesting to also use the manufacturer's utilities (Intel, AMD, NVIDIA, etc.).

Disable P2P connection for updates

Windows 10 and 11 are configured by default to use a P2P system for downloading updates , which means your PC can download patches from other computers and, in turn, share them with third parties.

This can result in CPU, RAM, and bandwidth usage that isn't always worthwhile. To disable it, go to Settings → Update & Security → Delivery Optimization and uncheck “Allow downloads from other computers”.

Free up disk space with Disk Cleanup

A nearly full hard drive or SSD not only makes life difficult for the user, but it also significantly complicates the work of the kernel and I/O subsystem , and increases internal fragmentation and virtual memory usage. You can learn how to free up space in Windows and improve performance.

The built-in Disk Cleanup tool is lightweight and reliable. Simply search for it in the menu, run it as administrator, select the drive, and check the boxes for the types of temporary and junk files you want to delete (temporary files, thumbnails, old caches, etc.).

It's advisable to use it at least once a month to prevent your system from becoming cluttered with residual files. Compared to resource-intensive third-party solutions, this tool consumes almost no resources and is perfectly safe.

Empty the recycle bin and delete temporary files

The recycle bin and temporary folders often act as a black hole where junk accumulates for months. Although it may seem harmless, all that content takes up space and can affect performance.

Emptying the Recycle Bin is as simple as right-clicking its icon and selecting "Empty Recycle Bin." For temporary files, go to Settings → System → Storage → This PC → Temporary files and click "Remove files."

CPU settings and resource saving: what really makes the difference

Beyond tweaking the kernel, many improvements come from reducing unnecessary CPU and RAM usage . Windows lets you control what runs at startup, what stays in the background, and how many visual embellishments you want to keep active.

If your processor is struggling or you have little memory, every application that starts automatically, every browser extension, and every useless service adds milliseconds of latency and constant resource consumption.

Remove programs you don't use

We often have many apps installed "just in case" that we never open again. Even if you don't use them, many leave behind resident processes and background services that drain resources without you noticing.

By going to Settings → Apps , you can review the full list and uninstall anything you don't need. For programs you do use but that constantly start processes, check if they allow you to disable background running or automatic updates.

Remove programs from Windows startup

Some applications are necessary, but they don't need to open every time you turn on your PC. Windows startup is a classic source of unnecessary resource consumption.

Open Task Manager (right-click on the taskbar or press Ctrl+Shift+Esc) and go to the "Startup" tab. From there, you can disable programs you don't need running . When you want to use them, you can open them manually, and in the meantime, they won't use CPU or RAM.

Reduce notifications and background apps

Constant notifications aren't just a nuisance: every app that can display alerts usually keeps processes running . To lighten the load, go to Settings → System → Notifications and actions and disable all those that aren't truly useful.

Also, in Settings → Privacy → Background apps, you can decide which apps can continue running when you're not using them. The fewer apps that run, the easier it is for the kernel to keep the system running smoothly.

Disable unnecessary animations and visual effects

The transitions, shadows, and animations look very impressive, but on less powerful systems they can put extra strain on CPU, RAM, and GPU resources . Windows allows you to adjust these effects from the classic control panel.

Right-click on “This PC”, go to “Properties”, and then to “Advanced system settings → Performance → Settings” . You can select “Adjust for best performance” and, if you want to maintain some readability, only re-enable “Smooth edges for screen fonts”.

Clean browser extensions and plugins

The browser is usually one of the biggest resource consumers, and extensions certainly don't help. Each extra plugin adds processes, memory, and potential leaks , which is especially harmful if you already have limited RAM.

In Chrome, go to Menu → More tools → Extensions and uninstall anything you don't use. In Firefox, go to "Add-ons." Don't be afraid to clean things up: you often don't even remember what half of them were for.

Advanced diagnostic tools: Performance monitor and bottlenecks

If you want to go a step further and understand what's really happening under the hood, Windows includes a very powerful tool: Performance Monitor . It doesn't speed up your system on its own, but it gives you very useful data to help you decide where to tweak things.

To generate a report, press Windows + R , type perfmon /report (on some systems the command appears as perform/report), and press Enter. The system will collect information for a few minutes and then display a detailed analysis.

It's helpful to start with the "Warnings" section , where you'll see key problems detected and suggestions: high CPU load, high disk latency, low memory, etc., and how to deal with a blue screen . In "Resource Summary," you can check the status of your CPU, disk, memory, and network at a glance.

If you see, for example, that the "disk tail length" remains above 2 with low load, or that the processor time percentage frequently hovers around 100% for no apparent reason, you already have clear clues as to where to investigate.

ReadyBoost, overclocking, and hardware upgrades: when it's worth it

When all software optimizations fall short, it's time to consider more drastic options: using auxiliary technologies like ReadyBoost, overclocking, or simply replacing components . Not all of these approaches are equally advisable.

ReadyBoost for systems with HDD and little RAM

ReadyBoost is a technology that uses a fast USB drive as an additional cache to speed up computers with mechanical hard drives . It won't work if your system already has an SSD, but it can be useful on very old machines.

All you need is a fast USB drive (at least 500 MB free) and to enable it from the drive's properties, ReadyBoost tab, by checking "Use this device." Windows will reserve a portion of the USB drive as a cache (ReadyBoost.sfcache file), and in certain scenarios, you may notice some improvement.

CPU overclocking: extra power with risks

Overclocking involves manually increasing the CPU's clock frequency (and sometimes the voltage) to extract more performance from the processor. When done correctly, it can result in a noticeable improvement, but it's not a harmless technique.

Increasing the frequency means higher power consumption and more heat. If the cooling system isn't up to the task, you could face overheating, instability, or even long-term damage . Furthermore, modifying voltages without proper control increases the risk of damaging other components.

For unlocked Intel processors (“K”), there's the official Intel Extreme Tuning Utility (XTU) , which centralizes overclocking options, stress tests, and real-time monitoring. Even so, it remains an option for intermediate/advanced users and not something suitable for everyone.

Upgrade your hardware: SSD and RAM are your best allies

If, despite all the adjustments, the system is still struggling, the problem is probably no longer with the kernel, but with the hardware. The most noticeable hardware improvements in day-to-day use are clear: switching from an HDD to an SSD and increasing the RAM.

A modern SSD dramatically reduces Windows and application load times and frees the kernel from dealing with endless disk queues. At the same time, expanding RAM allows you to open more programs without constantly entering paging mode , which eases the load on both the CPU and the memory subsystem.

It's also important to check that all components are working correctly: a faulty hard drive, a defective RAM module, or an insufficient power supply can cause slowness and crashes that no software adjustment will be able to completely fix, and it's advisable to monitor the temperature of your hard drives to rule out thermal failures.

Overall, fine-tuning how Windows boots and manages its kernel (fast startup, power plans, file caching), reducing unnecessary load (startup programs, notifications, visual effects), keeping the system up to date, monitoring bottlenecks with built-in tools, and, when necessary, strengthening the hardware, is the most reliable way to ensure your Windows PC responds smoothly, without unexpected pauses, and gets the most out of its configuration.