Is your Windows PC taking ages to start, opening programs slowly or freezing while you’re working? A slow computer can be frustrating, but the cause isn’t always obvious.
If you have a slow Windows computer, these checks can help identify what’s causing the problem.
Before spending money on repairs or replacing your computer, try these ten practical checks. We’ll start with simple steps and work towards possible software and hardware problems.
Using an Apple Mac? Windows and macOS work differently, so see our separate guide: Why Is My Mac So Slow?
Is it the computer, or just one application?
Sometimes it appears you have a slow Windows computer when the problem is actually limited to one program. For example, Outlook may take a long time to open, search for messages or respond when you click something. Other programs may continue working normally.
If one application is slow, check whether other programs and websites respond normally. If they do, concentrate on troubleshooting the affected application rather than assuming the whole computer needs repairing.
For Microsoft Outlook and other Office applications, check that the software is up to date. Updates can fix bugs and improve reliability and performance. If you use Microsoft 365, open an Office application and select File → Account → Update Options → Update Now, where those options are available.
If the problem continues, it may require application-specific troubleshooting. See our other iTech WA guides on updating Microsoft Office and resolving slow Office applications for further help.
If several applications are slow, or Windows itself takes a long time to respond, follow the 10 checks to investigate the wider problem.
If the computer is still slow, continue to the first check.
1. Restart your slow Windows computer
A restart can clear temporary problems and stop background processes that are no longer responding properly.
Save your open work, then select Start → Power → Restart. Allow Windows to shut down and start again completely.
A full restart is also important when Windows updates are waiting to finish installing. Closing a laptop lid or putting the computer to sleep is not the same as restarting it.
Once Windows has restarted, check whether performance has improved. If the computer is still slow, move on to the next step.
2. Check for Windows updates
Windows updates can include bug fixes, reliability improvements and security fixes. If your computer is having problems, check whether any updates are waiting to be installed.
Open Start → Settings → Windows Update in Windows 11, or Start → Settings → Update & Security → Windows Update in Windows 10. Check for available updates and follow the instructions if updates are offered.
Save your work before installing updates, and allow Windows to restart fully if required. A shutdown followed by starting the computer again is not always the same as selecting Restart.
Important: Windows 10 standard support ended on 14 October 2025. Eligible devices enrolled in Microsoft’s Extended Security Updates (ESU) programme can receive security updates for a limited time. Windows Update availability depends on your Windows version and support status.
Also check Advanced options and Optional updates. Review any available driver updates and select those that are appropriate for your computer. If you’re unsure whether an update is needed, check with your computer manufacturer before installing it.
3. Check which programs are using your computer’s resources
A program using too much processing power, memory or disk activity can make the whole computer feel slow.
Press Ctrl + Shift + Esc to open Task Manager (or select Task Manager from the menu) Select Processes if that tab is available, then look at the CPU, Memory and Disk columns to see whether a program is using an unusually large amount of a resource.
Don’t end unfamiliar processes simply because they appear near the top of the list. Windows needs many background processes to operate correctly. If a familiar application is not responding, save your work if possible and close that application normally before trying again.
4. Disable unnecessary startup apps
Some programs automatically start when you turn on your computer. Too many startup apps can increase the time Windows takes to start and leave fewer resources available for other tasks.
Press Ctrl + Shift + Esc to open Task Manager, then select Startup apps (or the Startup tab in some older versions of Windows). Review the list and disable apps you recognise and don’t need to start automatically.
Avoid disabling security software, backup tools or anything you’re unsure about. You can usually open a disabled app manually whenever you need it.
5. Check how much storage space is available
A drive that is almost full can make it harder to install updates and manage temporary files. Checking your available storage is a useful next step.
In Windows 11, open Start → Settings → System → Storage. In Windows 10, go to Start → Settings → System → Storage. Check how much free space remains on your main Windows drive, usually labelled C:.
If space is low, use Windows’ storage recommendations or Storage Sense to identify temporary files you can safely remove. Review files carefully before deleting anything, and back up important documents and photos before moving or removing them.
If your computer has plenty of free space but is still slow, continue to the next checks.
6. Check for malware and unwanted software
Malware and unwanted software can slow down a computer, cause unexpected pop-ups or make programs behave strangely.
First, check Windows Security. Open Windows Security → Virus & threat protection and check that Microsoft Defender Antivirus is working. Run a Quick scan to look for common threats.
For a second opinion, I also recommend Malwarebytes. I often use the free version to scan for malware and potentially unwanted software. It may sometimes identify items that another scan has missed.
Download Malwarebytes only from its official website. Install it, open the program and run a scan, following the instructions provided.
Remember that no security scanner detects every threat. Keep your security software up to date, and be cautious about unexpected warnings, unfamiliar programs and pop-ups offering to fix your computer. Avoid downloading unfamiliar “PC cleaner” or “speed booster” tools.
If a scan finds threats you cannot remove, or your computer continues behaving suspiciously, seek professional advice before making major changes.
7. Check whether your slow Windows computer is overheating
Computers can slow down when they become too hot. This may happen if cooling vents are blocked by dust, the computer is used on a soft surface, or its cooling system is not working properly.
Make sure the vents are clear and that the computer has room for air to circulate. Use a laptop on a firm, flat surface rather than a bed or cushion. Listen for unusually loud fans and watch for unexpected shutdowns.
Don’t open the computer or attempt internal cleaning unless you know how to do it safely. If the computer becomes excessively hot, shuts down repeatedly or makes unusual noises, it may need professional attention.
8. Could your slow Windows computer need a hardware upgrade?
The age of the computer alone doesn’t determine its performance. A computer with a suitable solid-state drive (SSD), enough memory and a healthy operating system may continue to work well for years.
However, if your computer still uses a traditional mechanical hard disk drive (HDD), replacing it with an SSD may significantly improve startup times and general responsiveness, provided the computer supports the upgrade.
Before buying a replacement computer, consider having it assessed. Depending on its condition and compatibility, upgrading the storage or memory may be worthwhile.
9. Check your browser and open tabs
Sometimes a computer isn’t actually slow — it’s the web browser that’s struggling. Browser-based applications, such as email, online accounting software and other web services, can use considerable memory and processing power. Having dozens of tabs open at once can make the problem worse.
Try closing tabs you no longer need, especially those running video, online meetings or complex web applications. Save any work first, as closing a tab may lose unsaved information.
If your browser remains slow, close it completely and reopen it. You can also restart the computer to clear temporary browser processes.
If the problem continues, try the browser’s built-in reset or settings restoration option. Be aware that resetting a browser may change settings or disable extensions, so check what will be affected before proceeding.
Keeping your browser up to date can fix problems and improve your device’s security. See our guide to Protect yourself from cyber attacks by updating Edge, Chrome and Firefox regularly
If only one website or web application is slow, the problem may be with that service or your internet connection rather than the computer itself.
10. Check for unwanted browser extensions
Unwanted browser extensions can cause advertising pop-ups, redirect searches, change your browser’s home page and make browsing slower. Some may be installed without you realising it, often alongside other software.
Open your browser’s extensions or add-ons settings and review the installed list. Remove extensions you don’t recognise or no longer need, but check their purpose before removing anything important.
In Microsoft Edge, open Settings → Extensions to review installed extensions. In Google Chrome, open the three-dot menu and select Extensions → Manage Extensions.
If you are seeing unexpected adverts, repeated redirects or suspicious browser behaviour, run a security scan as well. Removing an extension may solve the browser problem, but it won’t necessarily remove any underlying unwanted software.
Only install extensions from trusted sources, and be cautious when software installers offer to add browser extensions.
Use Windows’ built-in troubleshooters
Windows includes troubleshooting tools that can automatically check for certain problems and suggest or apply fixes. They won’t diagnose every cause of a slow computer, but they are worth trying before moving on to more advanced repairs.
In Windows 11, open Start → Settings → System → Troubleshoot → Other troubleshooters. Review the available troubleshooters and run any that relate to the problem you’re experiencing.
In Windows 10, open Start → Settings → Update & Security → Troubleshoot → Additional troubleshooters. The available options vary depending on your Windows version.
Follow the instructions provided by each troubleshooter. Some problems may require additional steps, and not every Windows installation includes the same troubleshooting tools.
If the computer is still slow, continue with the remaining checks or seek help diagnosing the cause.
Still having problems with a slow Windows computer?
If your slow Windows computer continues to freeze, displays system errors or struggles to start Windows, the problem may go beyond ordinary performance issues.
Read our guide to How to repair Windows for recovery options and ways to repair damaged Windows system files.
If you’re unsure which steps are safe for your computer, iTech WA can help diagnose the problem.
Looking for Mac troubleshooting advice?
If you use an Apple MacBook, iMac or Mac mini, see our separate guide: Why Is My Mac So Slow?.
Need help with your computer or technology?
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