The most common reasons your computer slows down
A slow computer usually comes down to one of three things: too many programs running at once, a hard drive that is nearly full, or malware or unwanted software taking up resources. Your computer has a limited amount of memory (RAM) and processing power, and when those fill up, everything else has to wait. The good news is that most slowdowns are fixable without replacing the machine.
Sometimes the slowdown is temporary—your computer is just busy doing something in the background, like updating Windows or scanning for viruses. Other times it is a sign that something is using resources it should not be, or that your storage space is running out. Knowing which one you are dealing with is the first step to fixing it.
Key Takeaways
- Check your Task Manager (Windows) or Activity Monitor (Mac) to see which programs are using the most memory and CPU power right now.
- A hard drive that is more than 85 percent full will slow down your computer noticeably, even if you do not notice the space filling up.
- Startup programs—apps that launch automatically when you turn on your computer—are often the hidden cause of slow performance.
- Malware and unwanted toolbars can run in the background and drain your computer's speed; a scan with Windows Defender or Malwarebytes can find them.
- If your computer is more than five or six years old, the hard drive itself may be failing, and a technician should check it before you lose data.
How to check what is using your computer's resources right now
The fastest way to see what is slowing your computer down is to open Task Manager on Windows or Activity Monitor on Mac. On Windows, press Ctrl + Shift + Esc at the same time. On Mac, press Command + Space, type "Activity Monitor," and press Enter.
Once it opens, look at the columns labeled "CPU" and "Memory." The programs listed at the top are using the most power right now. If you see something you do not recognize, write down the name and search for it online—that will tell you whether it is something you need or something you can close. Do not close anything unless you are sure what it is, because closing the wrong thing can cause problems.
If you see a program using 50 percent or more of your CPU or memory, that is likely your culprit. Right-click it and choose "End Task" (Windows) or click the X button (Mac) to close it. If it comes back the next time you restart, it is probably set to launch automatically, and you will need to remove it from your startup list.
Disable programs that launch when your computer starts
Many programs are set to start automatically when you turn on your computer, even if you do not use them every day. Each one takes a small amount of memory and processing power, and together they can add up to a noticeable slowdown. Disabling the ones you do not need is one of the fastest fixes.
On Windows, open Task Manager again (Ctrl + Shift + Esc), then click the "Startup" tab at the top. You will see a list of programs with a "Status" column that says "Enabled" or "Disabled." Right-click any program you do not use regularly and choose "Disable." Common culprits are Adobe Reader, Spotify, Slack, and various cloud storage programs. You can always turn them back on later if you need them.
On Mac, go to System Settings (or System Preferences on older versions), click General, then Login Items. You will see a list of programs that launch when you log in. Click the minus sign next to any you want to remove.
Check how much storage space your hard drive has left
When your hard drive is more than 85 percent full, your computer has to work much harder to find and organize files. This slowdown happens even if you are not actively using the full drive. If you have less than 10 to 20 percent of your drive free, that is likely part of the problem.
On Windows, open File Explorer, right-click "This PC" on the left side, and choose "Properties." You will see a bar showing how much space is used and how much is free. On Mac, click the Apple menu, choose "About This Mac," then click "Storage." If the bar is mostly full, you need to delete or move files.
Start by emptying your Recycle Bin (Windows) or Trash (Mac)—files there still take up space until you empty it. Then look for large files you no longer need: old downloads, duplicate photos, or videos you have already backed up. You can also uninstall programs you do not use anymore. On Windows, go to Settings > Apps > Apps & Features and click "Uninstall" next to anything you want to remove.
Scan for malware and unwanted software
Malware, spyware, and unwanted toolbars can run invisibly in the background and drain your computer's speed. They often come from free software downloads, suspicious websites, or email attachments. A malware scan will find most of them and remove them.
Windows comes with a built-in tool called Windows Defender. Open it by typing "Windows Defender" in your search bar, click "Virus & threat protection," then "Scan options." Choose "Full scan" and let it run—this can take 30 minutes or more, but you can use your computer while it works. If it finds anything, follow the prompts to remove it.
For a second opinion, you can also run a free scan with Malwarebytes, which catches some things Windows Defender misses. read it from malwarebytes.com, install it, and run a scan. Do not pay for the premium version unless you want real-time protection; the free version is enough for a one-time scan.
Update Windows and your drivers
Outdated Windows versions and drivers (the software that controls your hardware) can cause slowdowns and security problems. Windows usually updates automatically, but you can check manually to make sure you are current. On Windows, go to Settings > Update & Security > Windows Update and click "Check for updates." If updates are available, install them and restart your computer.
Drivers for your graphics card, network adapter, and other hardware can also be out of date. The easiest way to update them is to use a tool like Driver Booster (free version available) or to visit your computer manufacturer's website and read the latest drivers for your model. If you are not comfortable doing this yourself, a technician can handle it in 30 minutes or less.
When to replace your hard drive or call a technician
If your computer is more than five or six years old and you have tried all the steps above, the hard drive itself may be failing. Hard drives wear out over time, and a failing drive will slow your computer to a crawl even if nothing else is wrong. Warning signs include clicking or beeping sounds, files that disappear or become corrupted, or a computer that freezes randomly.
A technician can run a diagnostic test to check your hard drive's health in about 15 minutes. If it is failing, replacing it costs between $100 and $300 depending on the type of drive and your computer model. This is worth doing sooner rather than later, because a failing drive can fail completely without warning and you could lose all your files.
If you have tried the steps in this guide and your computer is still slow, and it is not making unusual sounds, the problem may be something more specific to your setup. A local computer repair shop can diagnose it in person for a fee, usually $50 to $100 for the diagnosis alone.
Frequently Asked Questions
Is it safe to disable startup programs?
Yes, as long as you only disable programs you recognize and do not use. If you are not sure what something is, search for the name online first. You can always turn it back on later if you need it. Avoid disabling anything with "Windows" or "System" in the name.
Will deleting files from my Downloads folder speed up my computer?
Only if your hard drive is very full. Deleting files frees up space, which helps if you are above 85 percent capacity. If you have plenty of free space, deleting old downloads will not make a noticeable difference in speed.
How often should I run a malware scan?
If you browse carefully and do not read from suspicious sites, once a month is enough. If you read a lot or visit risky websites, run a scan every week or two. Windows Defender runs automatically in the background, so you mainly need to do a full scan if you suspect a problem.
Can I speed up my computer by adding more RAM?
Yes, but only if your computer is actually running out of memory. Check Task Manager or Activity Monitor to see if memory is consistently above 80 percent. If it is, adding RAM will help. If memory is low but your computer is still slow, the problem is something else on this list.
What does it mean if my hard drive is making clicking sounds?
Clicking usually means the hard drive is failing and may stop working soon. Back up your important files when ready to an external drive or cloud storage, then have a technician check it. Do not wait—a failing drive can fail completely without warning.