A "slow" computer is almost never one big failure — it's several small things piling up. The good news is that the cheap, safe fixes come first, and they fix the majority of slow PCs. Work down this list; each step is quick and none of them risk your data.
Before you start
- Define "slow" for a second. Is it slow to start up, slow when opening apps, or slow when the disk works (a long wait on any file)? That points to the cause: startup, apps, or the drive.
- Don't reinstall Windows yet. That's the last resort and it wipes your settings. The fixes below are free and reversible.
- Have a backup before you do anything that involves cleaning or resetting, just in case.
Fix 1 — Cut the startup programs
This is the number one fix. Open Task Manager (right-click the taskbar → Task Manager, or Ctrl+Shift+Esc), go to the Startup tab, and disable anything you don't need at boot. A phone-sync app, a game launcher, a second antivirus — all of these fight to start at once and slow every boot.
You can't disable everything — keep your antivirus, your audio driver, and anything the PC needs to function. But 3–5 less startups is usually a very noticeable speed-up.
Fix 2 — Free up disk space
Windows gets dramatically slower when the system drive is nearly full, because it needs free space to work. Aim for at least 15–20% free on the drive Windows is on (usually C:).
- Settings → System → Storage shows what's taking space and offers a Clean up button.
- Empty the Recycle Bin.
- Uninstall apps you don't use (Settings → Apps → Installed apps).
- Move big files (videos, downloads) off the system drive if you have a second one.
Fix 3 — Check what's actually using the resources
Open Task Manager and look at the Processes tab, sorted by CPU, then Disk. If one process is pegged at 100% constantly, that's your culprit — it could be Windows Update, a Defender scan, or (less often) malware. A single runaway process makes the whole machine feel slow.
If you see a process you don't recognise using lots of CPU, search its exact name before you end it. Never end a process you're not sure about — that's how people break their system.
Fix 4 — Check the disk's health
A drive that's failing or an old mechanical drive (HDD) is the most common hardware cause of a slow PC. Signs of a failing drive: long freezes, clicking or grinding noises, files that won't open, or the PC hanging on startup.
If you have a mechanical hard drive, the single biggest upgrade you can make is to move to a solid-state drive (SSD). An SSD is typically 5–10× faster than an old HDD for everyday tasks, and it's one of the cheapest, highest-impact upgrades there is. If your PC is more than a few years old and still on an HDD, this is usually the fix that makes it feel brand new.
If you suspect the drive is failing (clicking, files vanishing, long freezes), back up your files first, before you do anything else. A failing drive gets worse, not better.
Fix 5 — Check your memory (RAM)
If you regularly run a browser with many tabs, office apps, and a few other things, 8GB of RAM is the modern comfortable minimum. If your PC has 4GB, it will feel slow when you do more than one thing at once. In Task Manager → Performance → Memory, you can see how much you're using. If it's consistently near 100%, more RAM (or a lighter set of running apps) will help.
When to get help or upgrade
If you've done the above and it's still slow, the likely remaining causes are a failing or mechanical drive (→ an SSD swap), too little RAM, or a CPU that's too old for your workload. The first two are cheap, worthwhile upgrades a technician or a confident DIYer can do. The third — a CPU that's simply outgrown — is a point where a newer PC is usually better value than a big upgrade.