What slows down a computer and how to fix it

A slow computer usually comes from one of four things: too many programs running at once, a hard drive that is nearly full, malware or viruses, or a hard drive that is wearing out. The first three you can fix yourself in an hour or two. The fourth means your hard drive needs replacement, which a repair shop can do for $100 to $300.

Start by checking what is actually running. Open your Task Manager (press Ctrl+Shift+Esc on Windows, or Command+Space then type Activity Monitor on Mac). Look at the CPU and Memory columns. If one program is using more than 50% of either, that is your bottleneck. If many programs are using small amounts, your computer is juggling too many tasks at once.

The second thing to check is how full your hard drive is. On Windows, open File Explorer, right-click This PC, and select Properties. On Mac, click the Apple menu, select About This Mac, then Storage. If the bar is more than 80% full, your computer has to work harder to find space for temporary files. Deleting old files, uninstalling programs you do not use, and moving large files (videos, photos) to an external drive or cloud storage will free up room.

Key Takeaways

  • Check Task Manager or Activity Monitor to see which programs are using the most CPU and memory, then close or uninstall the ones you do not need.
  • If your hard drive is more than 80% full, delete old files and uninstall unused programs to give your computer room to work.
  • Restart your computer weekly to clear temporary files and reset memory, which often solves slowness without any other changes.
  • Malware and viruses can hide in the background and slow your computer; run a full scan with Windows Defender or your antivirus software monthly.
  • If your computer is more than five years old and still slow after these steps, the hard drive may be failing and needs professional replacement.

Close programs that run in the background

Many programs start automatically when you turn on your computer and stay running even when you are not using them. Messaging apps, cloud storage, antivirus software, and browser extensions all do this. Each one uses a small amount of memory and CPU, and together they add up.

On Windows, open Task Manager (Ctrl+Shift+Esc), click the Startup tab, and look at the Impact column. Anything marked High or Medium that you do not use every day can be disabled. Right-click it and select Disable. On Mac, go to System Settings, General, Login Items, and remove programs from the Allow in the Login Window list.

Be careful not to disable your antivirus software or Windows Defender. Those need to run. If you are not sure what a program does, search its name online before disabling it.

Restart your computer weekly

Restarting clears temporary files, resets memory, and stops programs from accumulating in the background. A computer that has been running for weeks will be slower than one that restarts regularly.

Set a reminder to restart every Sunday evening or Monday morning. This takes five minutes and often solves slowness without any other work. If your computer is running slowly right now, restart it first before trying anything else.

Scan for malware and viruses

Malware and viruses can run hidden in the background, using your CPU and internet connection. They are often installed by clicking a link in an email or downloading from an unsafe website.

On Windows, open Windows Defender (search for it in the Start menu), click Virus & threat protection, then click Scan options. Select Full scan and click Scan now. This takes 30 minutes to an hour. On Mac, read Malwarebytes (it is free), install it, and run a full scan.

Run a full scan once a month, or when ready if your computer suddenly became slow or you clicked a suspicious link. If malware is found, the scanner will remove it automatically.

Uninstall programs you do not use

Every program you install takes up hard drive space and may run background processes. Uninstalling the ones you have not opened in months frees up space and removes unnecessary startup tasks.

On Windows, go to Settings, Apps, Apps & features. Scroll through the list and click Uninstall on anything you do not recognize or do not use. On Mac, open Applications, drag unused programs to the Trash, and empty the Trash.

Be careful not to uninstall anything that came with your computer or that you use regularly. If you are not sure, search the program name online first.

Move large files to external storage or cloud backup

Videos, photos, and large document files take up gigabytes of space. If your hard drive is nearly full, moving these to an external hard drive or cloud storage (like Google Drive, OneDrive, or Dropbox) frees up room and makes your computer faster.

External hard drives cost $50 to $100 and plug into your USB port. Cloud storage is usually free up to 15 GB (Google Drive, OneDrive) or 2 GB (Dropbox), with paid plans for more. Create a folder on your external drive or cloud service, drag your large files into it, and then delete them from your computer.

Keep a backup of important files in case your computer fails. Many people use both an external drive and cloud storage for this reason.

When to replace your hard drive

If your computer is more than five years old, has been restarted regularly, has plenty of free space, and is still slow, the hard drive itself may be failing. Hard drives wear out over time and slow down as they age.

Signs of a failing hard drive include clicking or grinding noises, files taking a very long time to open, or the computer freezing for several seconds at a time. If you hear these sounds or see these signs, stop using the computer and take it to a repair shop. A failing drive can lose your data if it stops working completely.

Replacing a hard drive costs $100 to $300 in labor and parts, depending on your computer type. A new hard drive (or solid-state drive, which is faster) will make an old computer feel almost new again.

Frequently Asked Questions

Why does my computer slow down after I have had it for a while?

Programs accumulate in the background, temporary files pile up, and your hard drive fills with old files you forgot about. Restarting weekly and uninstalling unused programs prevents most of this slowdown. If your computer is more than five years old, the hard drive itself may be wearing out.

Is it safe to disable programs in the Startup tab?

Yes, as long as you do not disable your antivirus software or Windows Defender. Most other programs can be disabled without harm. If you disable something and your computer stops working the way you expect, you can re-enable it the same way.

How often should I run a malware scan?

Once a month is a good routine. If you clicked a suspicious link, downloaded something from an unsafe website, or your computer suddenly became slow, run a scan when ready. A full scan takes 30 minutes to an hour.

What is the difference between a hard drive and a solid-state drive?

A hard drive has moving parts and is slower. A solid-state drive (SSD) has no moving parts and is much faster. If you replace a hard drive with an SSD, your computer will feel noticeably quicker. SSDs cost more but last longer and use less power.

Can I speed up my computer without restarting or uninstalling anything?

Not much. Restarting is the single most effective thing you can do, and it takes five minutes. Uninstalling one or two programs you do not use will also help. If you do neither, your computer will keep slowing down.