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A slow computer is frustrating, but it does not always mean you need to pay a repair technician. Many slowness problems are caused by things you can check and fix yourself, often for free. Before you spend money, work through these steps.
Check what is using your storage
A full hard drive makes everything slow. Open File Explorer on Windows or Finder on Mac, right-click on your main drive, and choose Properties (Windows) or Get Info (Mac). You will see how much space is used and available. If you have less than 10 per cent free space, your computer will run slowly.
Delete files you no longer need. Empty the Recycle Bin on Windows or Trash on Mac. Look for large folders: Downloads, Documents, Desktop, and Pictures. Move old photos and videos to an external drive or cloud storage. If you are unsure whether to delete something, move it to an external drive first rather than deleting it immediately.
Windows can also take up a lot of space with old system files. Go to Settings > System > Storage > Cleanup recommendations and let Windows remove temporary files and old Windows versions. This is safe and can free up several gigabytes.
Check what is running at startup
Every program you see running in the background slows down your machine. On Windows, right-click the taskbar and open Task Manager. Go to the Startup tab and disable programs you do not use. Look for Adobe Reader updates, Java updates, and other software you do not actively use. On Mac, go to System Settings > General > Login Items and remove programs from the Allow in the Login Window list.
Be cautious: only disable programs you recognise. If something is unclear, leave it.
Check your browser extensions
Browser slowness is often caused by extensions. Open your browser settings and look at the extensions or add-ons list. Disable ones you do not use. Password managers, ad blockers, and VPNs can slow browsing, especially on older computers. If your browser feels much faster after disabling extensions, you have found the problem: uninstall the slow ones.
Check for malware
Malware and viruses can make a computer run very slowly. Run a full scan with Windows Defender (Windows) or Activity Monitor (Mac). On Windows, go to Windows Security > Virus & threat protection > Scan options and select Full scan. This can take an hour, but it will check every file. On Mac, Activity Monitor can show if something is using unusual amounts of memory or CPU—look for processes taking more than 50 per cent CPU time.
When an SSD upgrade makes sense
If your computer still has a traditional spinning hard drive (HDD) instead of a solid-state drive (SSD), upgrading to an SSD is one of the biggest improvements you can make. An SSD will boot faster, open applications faster, and make everything feel more responsive. Signs you need an SSD upgrade include long boot times (over 2 minutes), grinding or clicking noises from the hard drive, freezes during file operations, and storage warnings.
However, before you pay for an upgrade, check Windows 10 and Windows 11 support dates. Windows 10 support ended in October 2025. If your machine cannot upgrade to Windows 11, an SSD upgrade may not be worth the expense, because your operating system will no longer receive security updates. In that case, replacing the computer may be a better investment than repairing it.
For macOS users, an SSD upgrade makes more sense, because Macs can usually update to the latest operating system for longer. A used Mac with an SSD upgrade can run well for several more years.
Check your internet speed
Sometimes the problem is not your computer but your internet connection. Use a speed test tool (such as Broadband.co.uk) to check your actual download speed. If your speed is much lower than your provider promises, restart your router or contact your internet service provider.
Get an expert opinion before spending money
If you have tried these steps and your computer is still slow, or if you do not feel confident doing this yourself, ask a repair technician to run diagnostics before quoting a price. A good technician will tell you what is causing the slowness and whether a repair or upgrade will actually fix it. Be skeptical of quotes for expensive upgrades or repairs if no one has explained what the actual problem is.
Key points
- A full hard drive or too many startup programs are the most common causes of slowness and are usually free to fix
- Disabling browser extensions and removing malware can dramatically improve performance
- An SSD upgrade is worthwhile if your drive is old, but check your operating system support dates first
- Before paying for repairs, get a clear explanation of what is causing the slowness
- If your computer is old and the operating system is no longer supported, replacing it may be cheaper than repair
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