Start with the fastest fixes first

A slow computer usually comes from one of three things: too many programs running at once, a hard drive that is nearly full, or malware. You can check and fix all three in under an hour, and most people see a real difference after the first step alone.

The single fastest fix is to restart your computer. When your machine runs for weeks without shutting down, programs pile up in memory and slow everything. A restart clears that out. If you have not restarted in more than a few days, do that first—before you do anything else on this list.

Key Takeaways

  • Restarting your computer clears programs from memory and is the fastest single fix for slowness.
  • Closing programs that run in the background—especially web browsers with many tabs—frees up memory when ready.
  • Deleting old files and emptying your recycle bin can speed up your hard drive if it is more than 80 percent full.
  • Running a malware scan with Windows Defender (built into Windows) or a free tool like Malwarebytes can find and remove programs slowing your system.
  • Disabling startup programs that you do not use every day prevents them from loading when your computer turns on.

Close programs running in the background

Every program you open uses memory, even if you are not looking at it. Web browsers are the biggest culprit—each tab uses memory, and 20 open tabs can slow your machine noticeably. Close browser tabs you are not using, then close the browser itself if you do not need it right now.

On Windows, open Task Manager by pressing Ctrl + Shift + Esc. Look at the "Memory" column—the programs at the top are using the most. If you see something you do not recognize or do not need running right now, click it and select "End Task." Common memory hogs include Spotify, Discord, Slack, and cloud backup services like OneDrive or Google Drive. You can always restart them later.

On Mac, open Activity Monitor by pressing Command + Space, typing "Activity Monitor," and pressing Enter. Click the "Memory" tab at the top. Look for programs using more than 500 MB. Click the program name and select the X button to close it. Be careful not to close anything with "kernel" or "system" in the name.

Delete files and empty your recycle bin

When your hard drive is more than 80 percent full, your computer slows down because it has no room to work. Check how full your drive is: on Windows, right-click the C: drive in File Explorer and select "Properties." On Mac, click the Apple menu, select "About This Mac," then click "Storage."

If you are above 80 percent, delete files you no longer need. Start with your Downloads folder—most people have gigabytes of old installers and documents there. Move large files like old videos or photos to an external hard drive or cloud storage like Google Drive or OneDrive. Then empty your recycle bin (Windows) or Trash (Mac) to actually remove the files from your drive.

If you are unsure what to delete, use a disk cleanup tool. On Windows 10 or 11, type "Disk Cleanup" in the search box and open it. Select your C: drive and click "OK." Check the boxes next to "Temporary files," "Recycle Bin," and "Temporary internet files," then click "Delete Files." This is safe—it removes only junk files.

Run a malware scan

Malware—unwanted programs that slow your computer or steal information—is common and often invisible. Windows comes with a built-in scanner called Windows Defender that is free and effective. Open it by typing "Windows Defender" in the search box and selecting "Windows Security."

Click "Virus & threat protection," then click "Scan options." Select "Full scan" and click "Scan now." A full scan takes 30 minutes to an hour, so start it and do something else. When it finishes, Windows Defender will tell you if it found anything and remove it automatically.

If Windows Defender finds nothing but your computer is still slow, read Malwarebytes (the free version) from malwarebytes.com. Install it, open it, and click "Scan." This catches some threats Windows Defender misses. Malwarebytes is safe and does not slow your system.

Turn off startup programs

Many programs are set to start automatically when you turn on your computer, even if you do not use them every day. Each one adds seconds to your startup time and uses memory while running. Disabling the ones you do not need is a quick win.

On Windows 10 or 11, right-click the taskbar at the bottom and select "Task Manager." Click the "Startup" tab. You will see a list of programs with a "Status" column showing "Enabled" or "Disabled." Right-click any program you do not use every day—like Spotify, Adobe Reader, or Zoom—and select "Disable." You can always start these programs manually when you need them.

On Mac, click the Apple menu, select "System Settings," then click "General" in the sidebar. Click "Login Items." You will see a list of programs that start automatically. Click the X next to any you do not need, or select it and click the minus button below.

Update Windows or macOS

Operating system updates often include speed improvements and security fixes. Check for updates regularly. On Windows, type "Check for updates" in the search box and open it. Click "Check for updates." If updates are available, install them and restart your computer.

On Mac, click the Apple menu, select "System Settings," then click "General" in the sidebar. Click "Software Update." If updates are available, click "Update Now" or "Upgrade Now" and restart when prompted.

Consider upgrading your hard drive or adding memory

If your computer is still slow after trying all the steps above, the hardware itself may be the limit. Computers with less than 8 GB of memory or an older mechanical hard drive (not a solid-state drive, or SSD) run slowly even when nothing is wrong.

Adding memory or replacing a mechanical hard drive with an SSD is the most effective long-term fix, but it requires opening your computer or paying a technician. If your computer is more than five years old and still running a mechanical hard drive, an SSD upgrade will make the biggest difference—often cutting startup time from two minutes to 20 seconds.

If you are not comfortable opening your computer, take it to a local repair shop and ask for a quote on adding memory or upgrading to an SSD. The cost is usually between $100 and $300, and the speed improvement is dramatic.

Frequently Asked Questions

How long should a computer restart take?

A normal restart takes 30 seconds to two minutes on a modern computer. If yours takes longer, your hard drive may be failing or you have too many startup programs. Try disabling startup programs first. If restart time does not improve, back up your files and consider having a technician check your hard drive.

Is it safe to disable programs in Task Manager?

Yes, as long as you do not close anything with "Windows," "System," or "svchost" in the name. Those are core operating system processes. Everything else is safe to close—the worst that happens is a program stops working and you restart it. You can always restart your computer if something goes wrong.

Will clearing my cache and cookies speed up my browser?

Slightly, but only if your cache is gigabytes in size. In most cases, closing extra browser tabs and restarting your browser does more. If you want to clear cache anyway, open your browser settings, find "Clear browsing data" or "Clear history," check "Cached images and files," and click "Clear."

What is the difference between restarting and shutting down?

A restart turns your computer off and back on, which clears memory and reloads the operating system. A shutdown just turns it off. If you want to clear memory and speed things up, restart. If you are done for the day, shutdown is fine.

Can I speed up my computer without restarting?

You can close programs and delete files without restarting, and both will help. But a restart clears memory more completely and is the single fastest fix. If your computer is slow, restart first—it takes two minutes and usually makes a real difference.