Slow Windows PC? 7 checks to run before you pay for a repair

A slow computer is one of the most common reasons people bring a machine to us. Sometimes it genuinely needs a repair or an upgrade. Often, though, the cause is something you can find yourself in a few minutes with tools that are already built into Windows 11.

Here are the seven checks we'd run first. Work through them in order; each one takes between one and ten minutes. Before you start, make sure your important files are backed up — it's good practice before changing anything on a computer.

1. Do a proper restart

It sounds too simple, but it's the right first step. Restarting clears out apps and processes that have built up in memory, and it finishes installing updates that are waiting.

There's a catch worth knowing: on many PCs, Shut down doesn't fully restart Windows, because a feature called Fast Startup saves part of the system state to speed up the next boot. Restart does a full restart. So use Start > Power > Restart, not shut down and power on again.

If the PC is fine for a while after restarting and then gets slow again, that's a useful clue: something is building up over time, which the next checks should help you find.

2. See what's actually using the PC

Open Task Manager by pressing Ctrl + Shift + Esc.

• On the Processes page, select the CPU, Memory and Disk column headings to sort by each one. Look for anything consistently near the top while you're not doing much.
• On the Performance page, check whether CPU, memory or disk is sitting close to 100% for long periods.

What you find points to the next step. A single app eating memory might just need closing or updating. Memory that's always full while running your normal set of apps suggests the PC needs more RAM. A disk that's constantly at 100% is worth investigating under check 7.

Don't end processes you don't recognise just to see what happens; search the exact name first, or ask someone who knows.

3. Trim your startup apps

Many apps add themselves to startup, so they load every time you sign in, whether you need them or not. Microsoft notes that apps running at startup can slow boot time and increase background activity.

• Go to Start > Settings > Apps > Startup and switch off apps you don't need straight away, or
• In Task Manager, select Startup apps, right-click an app, and choose Disable. Task Manager also shows a Startup impact rating for each one.

Disabling an app here doesn't uninstall it; it just stops it loading automatically. Keep your security software and anything your business relies on (such as backup or sync tools) enabled.

4. Free up disk space

When the system drive gets nearly full, Windows has less room for temporary files and updates, and performance can suffer. Microsoft also notes that low space can cause trouble installing updates.

1. Go to Start > Settings > System > Storage to see how much space is free.
2. Select Temporary files, tick what you want to remove, and select Remove files.
3. Turn on Storage Sense to clean up temporary files automatically, or select Run Storage Sense now.
4. Check Cleanup recommendations on the same page for large unused files and apps.

While you're there, go to Start > Settings > Apps > Installed apps and uninstall software you no longer use. Fewer apps usually means less background activity, too.

5. Install Windows and driver updates

Updates include security fixes and, often, performance and reliability improvements.

1. Go to Start > Settings > Windows Update and select Check for updates.
2. Install anything available and restart if asked.
3. Then go to Advanced options > Optional updates to see whether there are driver updates for your hardware.

If your PC came from a major manufacturer, its own support app may offer firmware and driver updates too. Only install drivers from Windows Update or the manufacturer's official website.

6. Run a malware scan

Malware can consume processor and disk resources in the background. Windows 11 includes Microsoft Defender Antivirus as part of Windows Security.

1. Go to Start > Settings > Privacy & security > Windows Security > Virus & threat protection.
2. Select Quick scan.
3. If you have reason to be suspicious — pop-ups, a changed browser homepage, unfamiliar apps — select Scan options and run a Full scan, or the Microsoft Defender Antivirus (offline scan), which restarts the PC to scan before Windows loads.

If you have a separate security product installed, run its scan instead, and make sure you're not running two real-time antivirus products at once, which can slow things down on its own.

7. Check what kind of drive you have, and its health

This is the check that most often explains a slow older PC. Computers with a traditional spinning hard drive (HDD) are much slower to start and open apps than those with a solid-state drive (SSD).

Find out which you have: In Task Manager, go to Performance and select your disk. The details below the graph include Type, which shows SSD or HDD.

Check its health: Open Windows PowerShell or Terminal and run:

Get-PhysicalDisk | Select-Object FriendlyName, MediaType, HealthStatus

This lists each physical drive, whether it's an SSD or HDD, and the health status Windows reports. Anything other than Healthy deserves attention soon — make sure your backups are current first.

You can also check that Windows is maintaining the drive: search for defrag and open Defragment and Optimize Drives. Windows optimises drives automatically by default — defragmenting hard drives and running TRIM on SSDs — and this window shows when it last ran.

When it's time for a repair or upgrade

If you've worked through all seven and the PC is still slow, the cause is most likely hardware. Typical signs:

• The system drive is an HDD — moving to an SSD is often the single biggest improvement for an older machine.
• Memory is consistently full with your normal workload.
• The drive health isn't reported as Healthy, or you hear clicking from inside the case.
• It slows down badly when it gets warm, which can point to dust build-up or cooling problems.
• Microsoft itself notes that older PCs with outdated hardware may not see much improvement from these steps, and replacing the device can be the better long-term option.

That's where a diagnostic helps: it tells you whether a repair or upgrade is worth it before you spend money.

Where People's Digital fits

You can book a diagnostic or repair through our client portal and follow it through to collection. For businesses, our Business Care plan (£90/month) includes monthly checkups, update monitoring and priority support, so problems like these get spotted before they slow your team down.