
Trying to figure out why your computer is running slow? High disk usage can make loading websites, files and programs take too long, and the cause could be as dangerous as a virus or malware infection.
Your PC can use a significant amount of resources to run read/write operations, which leads to your device running at a snail’s pace and causing it to crash frequently. Sometimes, a malicious application hiding on your computer can take up these resources.
Other problems include running multiple programs simultaneously, downloading or uploading large files, outdated drivers and unnecessary services on your PC running in the background.
If you’re reaching 100% disk usage, you’ll need to fix it immediately.
This guide will help you fix high disk usage on your computer and explain how the best antivirus software can return your PC to normal.
High disk read/write usage: Quick fixes
There are several ways to fix high disk usage and to speed up your computer’s performance. Follow the simple steps below to fix the issue.
It’s important to note that we recommend trying each step. Even if you get your disk usage back to normal, malicious software could be hiding in plain sight to force high disk usage again – bringing you back to square one.
-
Remove the process causing high disk usage
Knowing what app or background process is causing high disk activity will help you solve the problem. Once you identify what’s taking up a significant amount of read/write operation resources, you can quickly stop the process.
To do this, you’ll need to open Task Manager. Press CTRL + SHIFT + ESC or right-click on the taskbar and select Task Manager to open the app.
Click on the Disk tab to see all running apps and background processes in order of disk usage.
If a process is highlighted orange and runs over 1MB/s or 2MB/s, it takes up a lot of disk usage. If you see anything near 100% disk usage, these will contribute to this and need to be stopped. This is especially true if there’s an unfamiliar process running without you realising it.
Right-click the app or background process taking up resources and select End task.
-
Disable unnecessary background services
Windows and third-party services use many processes that work in the background. While many of these can be helpful, some can take up a lot of system resources and cause high disk usage, slowing down your PC.
One way to lighten the load is to stop apps or background processes you don’t need via Task Manager. An excellent way to find unnecessary programs using disk activity is to head into Start-up apps. Go to Task Manager > Start-up apps in the left-hand sidebar and search for any apps you don’t need running. Then right-click and select Disable.
Other Windows processes can also cause unusually high disk usage, which can be disabled in another way. For example, SuperFetch and Windows Search are known to increase your system load unnecessarily.
SuperFetch, or Service Host SuperFetch, analyses system usage patterns and preloads data from apps and programs to make them easier to access. However, it can also cause consistently high data usage. To disable it, click start and type Services and select the app. Scroll down to SysMain and double-click on it. Next to Startup type, click the drop-down menu and select Disabled.
Windows Search lets you search for files on your computer much faster but can also increase the load. If you don’t need it, head into Services and double-click Windows Search. Like before, use the drop-down menu and click Disabled.
-
Defragment and check your hard drive
If there are no problems with system processes affecting disk usage, there could be an issue with the hard drive itself. The good news is this can be fixed with a few simple clicks.
You can check for hard disk errors and repair problems through the CHKDSK tool. What’s more, using the same method, you can defragment to optimise your computer’s drive. This will rearrange files on your disk so they are stored more efficiently.
Head to File Explorer > This PC > right-click and select Properties on your chosen drive > Tools tab. From here, you can select Check under Error checking and Optimise under Optimise and defragment drive.
If you get a message stating, “Restart your computer to repair file system. You can restart right away or schedule the error fixing on next restart,” follow the instructions to fix the issue.
To be safe, make sure you have your hard drive data backed up so you don’t lose any important data.
-
Update your software and restart your computer
Updating your Windows PC software and restarting your computer can often fix unexpected high disk usage problems. However, they can also fend off malicious software.
Cybercriminals take advantage of security vulnerabilities on your device. These zero-day vulnerabilities allow threat actors to exploit computer systems until developers mitigate them, which can cause major damage.
Updating your system’s software can resolve the issue. A software update often contains security patches that help protect your device, as developers work to protect users from known zero-day attacks and other forms of malware trying to infect your device, especially with unfamiliar processes.
You can update your device through its settings. For example, you can update your Windows PC by navigating to Start > Settings > Windows Update > Check for updates. If there are any, download and install the update.
-
Change your passwords
If you’re experiencing a slow PC with high disk usage and nothing will fix it, chances are your PC has been infected with a virus or malware, and your online accounts and devices are at risk of being compromised.
To help mitigate potential malware threats or hackers taking control of your accounts, change your passwords and use a strong password to stop suspicious activity.
Using password managers such as LastPass or 1Password can help manage all your passwords in one place, create a complex, near-unbreakable master password and encrypt your information.
Changing passwords will stop hackers from trying to steal any sensitive information and your online accounts.
-
Use antivirus software to detect and stop malware
If you can’t find any way to solve high disk usage, using one of the best antivirus software like Norton 360 (from $19.99/year) will keep you safe from any malicious software, like ransomware, adware, spyware, phishing and more.
That’s not all; antivirus software can provide extra features like VPNs, dark web monitoring and more. Norton 360 has all these features and extra security tools that can backup your data, prevent online identity theft and stop malware.
What’s more, Norton 360 comes with monitoring features to identify all suspicious activity on your device. Select packages also feature cloud storage to help you save hard drive space and a PC booster like Norton Utilities Ultimate to, well, boost PC speeds and stop high disk usage. It will help detect and notify you about any unusual activity and stop it using it’s protection tools.
Check out our Norton 360 review and Norton 360 Platinum review to see which antivirus package suits you best.
Why is my disk usage so high?
Plenty of issues can cause extremely high disk usage, including seeing 100% disk activity. Some can contribute to a temporary high load, but if you’re seeing consistently high disk usage, it needs to be fixed.
When running multiple, high-demanding programs at the same time, they all need access to your disk to load files, data and different apps. This leads to an overload of disk usage, causing your PC to slow down or even crash. Running large files like games or intensive apps can cause this.
Downloading and uploading large files requires your disk to read and write data to and from your computer. If you’re downloading and uploading multiple large files at once, like photo or video files, it can take up a significant amount of resources.
Apps and background processes can also use an unnecessary amount of disk activity, even when you don’t need them running. Sometimes, it can be a problem with the process itself, meaning a quick restart or update could fix it.
Unfortunately, there’s the risk of a virus or malware causing an unexpectedly high amount of disk usage. Malware can sneak onto your device through a number of ways, including mistakenly clicking a suspicious link in an email or going to a dodgy website. Once malware is downloaded, it can hide on your device and run in the background unnoticed, sneakily taking up resources.
To identify and remove malicious software and prevent infections, it’s best to use an antivirus like Norton 360 to detect any malicious activity and stop the malware from causing more harm.

How can I fix 100% disk usage in Windows?
If you see 100% disk usage on Task Manager, your disk has reached its maximum capacity and can no longer deal with any other tasks. This isn’t ideal, as it can cause your PC to crash, and it may not recover.
The most important step in fixing this is to identify the problem’s cause, which can be done by heading to Task Manager and figuring out what processes are causing disk activity to reach 100%.
Stopping apps and background processes can help, but you should also let Windows diagnose and resolve the issue using the CHKDSK tool – as mentioned in our fixes. Making sure your hard drive is optimised is also an excellent way to prevent such high disk usage, so try defragmenting your drive.
If the problem happens unexpectedly and is now a consistent issue, using an antivirus scanner can track down any unfamiliar or malicious activity on your device. Moreover, you can use a PC booster to boost system speeds.
Do PC boosters actually work?
It can be a pain to figure out why your PC is acting slower than usual, especially if many apps and programs have been installed over the years. However, a PC booster like Norton Utilities Ultimate (from $39.99/year) can take the legwork out of cleaning up your files and disabling the right processes.
Norton’s PC cleaner and optimizer tool for Windows computers can help clear out junk files, find unwanted software needlessly taking up space, turn off programs slowing down your system and even clean up browser data.
Its selection of advanced tune-up tools and simple yet effective user interface make it a fantastic option for anyone looking to give their computer a much-needed boost – and keep it that way.
There are free PC cleaners around, but they will provide fewer handy features to keep your PC in prime condition. Check out our Norton Utilities Ultimate review for a better look at how it performs.
Can any antivirus software stop viruses and malware?
The best antivirus software will stop malware in its tracks. Not all antivirus software is equal, as some don’t have high malware detection and protection rates or have accredited lab scores to back them up.
However, many high-standard AV protections offer near-perfect scores when detecting and protecting against malware, meaning even complex malicious software can’t go unnoticed. Even if it’s a hidden app running in the background and causing high disk usage, an antivirus will be able to detect and eliminate it.
Services, including Norton 360 (from $19.99/year) and Bitdefender (from $19.99/year), include device monitoring features to help uncover suspicious activity early and offer the tools to fight off cyberattacks. Whether its a phishing attack, ransomware, spyware or infostealer malware, these security products have the tools to protect you.
These services have protection features that block malicious activity on your device, along with extra features like cloud backup and PC boosters. To make sure your device is ready to identify and block malware damaging your system, set yourself up with an antivirus.
Best antivirus to prevent viruses and malware
1. Norton 360 🥇From $19.99/year
Best overall antivirus of 2023

“Norton” and “antivirus” are synonymous these days, as the well-established cybersecurity brand has successfully fought against malware, viruses and nasty software threats since 1990.
Norton 360 offers excellent antivirus protection and extra features that make for a valuable, all-in-one security product. Its Norton 360 Deluxe and Premium package may cost a pretty penny. Still, with security across multiple platforms, a full-blown VPN, Dark Web Monitoring, Parental Controls and more, it will have a household free of cyber threats.
Norton’s certainty of its antivirus software’s capabilities is clearly defined by the brand’s 100% Virus Protection Promise. If a device protected by Norton 360 can’t get rid of a virus, the user receives their money back. It’s a big claim, but unquestionably, no one should expect to get that refund.
If you have the money for it, you can also check out the premium Norton 360 Platinum package for even more online protection, including from identity theft. Without a doubt one of the best antivirus to get.
Read our full Norton 360 review
Special Offer!
2. Bitdefender 🥈 From $19.99/year
Best security features and tools

Bitdefender takes the spot as best antivirus, and for good reason. It’s not enough that it boasts near-perfect lab test scores across the board, as it goes the extra mile by giving users access to a plethora of advanced security features.
Bitdefender goes above and beyond in the features department, all while keeping known malware, ransomware, and viruses at bay. It will defend your device against new attacks, provide security for online transactions, keep you safe with a reliable VPN, and protect your accounts with a password manager.
It’s a no-brainer when it comes to defending your devices against virtually any form of cyberattack, and its top-notch protection extends to its most affordable package, too. Protecting your PC and smartphone, from Windows and macOS to iOS and Android, is becoming even more necessary, and Bitdefender is the tricked-out shield you need.
Read our full Bitdefender review
Special Offer!
3. Malwarebytes 🥉 From $44.99/year
Best antivirus for Windows PC

Hundreds of malware emerge every minute, and it’s Malwarebytes’ mission to detect and conquer them all. Does the antivirus do this successfully? Yes, but there’s wiggle room for improvements.
Malwarebytes’ no-nonsense approach to protecting your devices from the onslaught of malware and viruses is effective for those who need a reliable antivirus that will detect and remove malicious software, especially with its free version. However, while its premium service provides 24/7 real-time detection, conveniently blocks vicious ransomware and shields users from malicious websites, it doesn’t go beyond on the feature front.
That’s no bad thing, as sometimes a user only needs a powerful antivirus to keep them safe from cyber threats. But considering its competitors add a few more security tools, such as data breach monitoring and a firewall, there’s room for improvement.
Read our full Malwarebytes review
Special Offer!
4. Avast One 🙌 From $39.99/year
Best antivirus for beginners + free plan available!

With Avast One, you can protect your device from viruses, malware and ransomware for free. That’s right, and you don’t have to pay a dime for the extra security features the antivirus throws in, including its VPN, firewall and more.
Avast One will safeguard your device from malware, comes with ransomware protection, blocks harmful websites and downloads from the web, scans your emails for malicious attachments, stops hackers from infiltrating your device through Wi-Fi with a firewall – the list goes on. That’s a lot of tools for software that’s free, and the included VPN and the ability to speed up your PC are a welcome bonus.
It’s the ideal antivirus software for home use, as it takes the hassle out of staying wary of cyber threats lurking around, even if you’re not a tech whizz. What’s more, if you are looking for added precautions, its paid Individual and Family packages still boast great value. Hard to go wrong with this best antivirus.
Read our full Avast One review
Special Offer!
5. AVG👍 From 4.99/month
Best antivirus for + free plan available!

You can never go wrong with free antivirus protection, but some deliver even better detection and protection rates, along with extra security features, without costing a dime. This is where AVG antivirus shines.
AVG provides reliable protection and only a small impact on performance for Windows, Mac, iOS and Android. It safeguards your devices against malware, viruses and zero-day exploits, along with blocking malicious links and attachments in emails. Throw in phishing protection when surfing the internet and extra security features such as its SafePrice browser extension and Network Inspector, and you’ve got yourself a do-it-all antivirus.
Sure, you can find all of these perks with Avast, but if you like a slick, darker user interface that’s easy to navigate, then AVG is for you.
Read our full AVG Antivirus review
Special Offer!