Before you buy a new computer or download some "PC Cleaner Pro Ultimate" that will make things worse, try this list. A slow PC is almost always suffering from one of about a dozen fixable problems, and every fix below is free, built into Windows, and reversible. Work top to bottom — the list is ordered by how often each fix is the culprit.
- Cut Down Startup Programs
The #1 cause of "my PC takes five minutes to boot." Press Ctrl+Shift+Esc, go to the Startup tab, and disable everything you don't need the second you log in. Game launchers, chat apps, updaters — they'll still work when you open them; they just won't ambush your boot time.
- Check What's Actually Eating Resources
In the same Task Manager, check the Processes tab. Sort by CPU, then Memory, then Disk. If one app is pinning a resource at 100%, you've found your problem. Disk at 100% constantly is a special case — see fix #11.
- Restart Properly (Not Shut Down)
Strange but true: Windows "Fast Startup" means shutting down doesn't fully reset the system, but Restart does. If your PC has been "shut down" daily for weeks but never restarted, restart it. Many mystery slowdowns end here.
- Free Up Drive Space
Windows slows noticeably when your system drive is nearly full. Open Settings → System → Storage, turn on Storage Sense, and run its cleanup. Empty the Downloads folder graveyard while you're there. Aim to keep at least 15–20% of your drive free.
- Uninstall What You Don't Use
Settings → Apps → Installed apps, sort by size, and be ruthless. Pre-installed bloatware, that game you finished a year ago, three different video converters from one panicked afternoon in 2023 — out.
- Disable Visual Effects
Search "adjust the appearance and performance of Windows" from the Start menu, choose Adjust for best performance, then manually re-enable "Smooth edges of screen fonts" so text doesn't look terrible. On older machines this feels like a hardware upgrade.
- Scan for Malware
Crypto-miners and adware love to hide on slow PCs — sometimes they're why it's slow. Run a full scan with Windows Security (it's genuinely good now and already installed): Settings → Privacy & security → Windows Security → Virus & threat protection → Full scan.
- Update Windows and Drivers
Counter-intuitive when updates are often blamed for slowdowns, but stale graphics and chipset drivers cause stutter, and pending updates running in the background eat resources until installed. Let them finish, restart, then judge performance.
- Clear Your Browser
If "my PC is slow" really means "Chrome is slow," the fix is different: remove extensions you don't use, close the 47 tabs (bookmark them, they'll be fine), and clear cached data. Browsers are the heaviest app most people run.
- Check Your Power Plan
Laptops especially ship in battery-saver modes that throttle performance. Settings → System → Power & battery, and set it to Best performance when plugged in.
- The One Hardware Upgrade That Changes Everything
If your PC has a mechanical hard drive (you'll hear it clicking, and Task Manager's disk column lives at 100%), replacing it with an SSD is the single biggest speed upgrade in computing. It transforms 8-year-old machines. SSDs are cheap now, and cloning your old drive over takes an afternoon. If your PC already has an SSD but only 4–8GB of RAM, a RAM upgrade is the next best move.
- The Nuclear Option: Reset Windows
When all else fails, Settings → System → Recovery → Reset this PC with "Keep my files" gives you a fresh Windows install without losing documents. Back up first anyway. A reset clears years of accumulated cruft in about an hour and is far better than living with a slow machine out of fear.
What NOT to Do
Don't download registry cleaners or "PC boosters." They range from useless to actively harmful, and several are malware wearing a suit.
Don't disable your antivirus for speed. The risk massively outweighs the tiny gain.
Don't defragment an SSD. It does nothing helpful and adds wear. (Windows already handles drive optimisation automatically.)
FAQ
Why is my computer so slow all of a sudden?
Most common causes: a Windows update installing in the background, a program misbehaving (check Task Manager), malware, or a drive that's nearly full.
Does more RAM make a computer faster?
Only if RAM is your bottleneck. If Task Manager shows memory usage above ~85% during normal use, yes. If not, more RAM changes nothing.
How often should I restart my PC?
A proper restart once or twice a week keeps Windows healthy. "Shut down" with Fast Startup enabled doesn't count.
Is it worth upgrading an old PC or buying new?
If it has a hard drive, an SSD upgrade buys 2–3 good years for very little money. If it already has an SSD and still crawls, the rest of the hardware is likely past it.