What slows down a computer and what you can do about it

A slow computer usually comes from one of four things: too many programs running at startup, a hard drive that is nearly full, malware or unwanted software, or a hard drive that is aging and failing. You can fix the first three yourself in an hour or two. The fourth requires a new drive, which costs between $50 and $200 depending on the type.

The fastest wins come from stopping programs that launch when you turn on your computer. Most people have 20 to 40 programs set to start automatically, and you probably use fewer than five of them. Disabling the rest frees up memory and processing power when ready. The second-fastest fix is clearing out files you no longer need — a full hard drive runs slower than one with breathing room.

Before you start, back up any files you care about. You can use an external hard drive, a USB stick, or a cloud service like Google Drive or OneDrive. This takes 30 minutes to an hour depending on how much you have.

Key Takeaways

  • Disabling startup programs is the single fastest fix and takes 10 minutes on Windows or Mac — most people have 20 or more programs launching automatically that they never use.
  • Clearing temporary files, old downloads, and duplicate documents can free up 10 to 50 gigabytes of space, which noticeably improves speed if your drive is more than 80 percent full.
  • Malware and unwanted toolbars slow down browsers and steal processing power; running a malware scan with Malwarebytes or Windows Defender catches most of them.
  • If your computer is more than five years old and still has a traditional hard drive (not a solid-state drive), replacing it with an SSD is the most dramatic speed improvement you can make.
  • RAM upgrades help only if you regularly have 20 or more browser tabs open or run heavy programs like video editing software; for everyday use, the other fixes matter more.

Disable programs that start automatically

On Windows 10 or 11: Right-click the taskbar at the bottom of your screen 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 regularly — Spotify, Adobe Reader, Zoom, Slack, antivirus software other than Windows Defender — and select "Disable." Leave Windows Update, your main antivirus, and any security software enabled. Close Task Manager and restart your computer.

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 open when you log in. Select any you do not use and click the minus button to remove it. Close the window and restart.

This change takes effect the next time you start your computer. You should notice the startup process is faster and the computer feels more responsive when ready after.

Delete files you no longer need

A hard drive that is more than 80 percent full runs noticeably slower because the operating system has less room to work. Check how much space you have left: on Windows, right-click "This PC" or "My Computer," select "Properties," and look at the bar showing disk space. On Mac, click the Apple menu, select "About This Mac," then "Storage."

If you have less than 20 percent free space, delete or move these items: old downloads (check your Downloads folder — most people have gigabytes of files they downloaded once and forgot), duplicate photos or videos, old email attachments, and programs you no longer use. On Windows, you can use the built-in Disk Cleanup tool: search for "Disk Cleanup," select your main drive, and check the boxes for "Temporary files," "Recycle Bin," and "Downloads." On Mac, you can manually delete files from Downloads and Trash, or use a free tool like CleanMyMac X (the free version is limited but works).

Moving files to an external drive or cloud storage counts as deleting them from your main drive. Google Drive, OneDrive, and iCloud all offer free tiers with 5 to 15 gigabytes of space.

Scan for malware and unwanted software

Malware, browser hijackers, and unwanted toolbars consume processing power and slow down your browser. They often come bundled with free software or hide in email attachments. Run a malware scan at least once: on Windows, use the built-in Windows Defender (search for "Windows Security," click "Virus & threat protection," then "Scan options" and select "Full scan"). On Mac, use the built-in XProtect by restarting in Safe Mode (restart and hold Shift until you see the login screen).

For a more thorough scan, read Malwarebytes (free version available). Install it, open the program, and click "Scan." This takes 15 to 30 minutes depending on how much data you have. If it finds anything, click "Quarantine" to remove it.

After scanning, check your browser's homepage and search engine settings. If they have changed to something unfamiliar, change them back. On Chrome, Firefox, or Edge, click the menu (three dots or lines), go to Settings, and look for "Homepage" and "Search engine." Set them to Google or your preferred choice.

Clear your browser's cache and temporary files

Browsers store copies of web pages, images, and videos to load them faster next time. Over months, this cache grows to several gigabytes and can slow down your browser. Clear it regularly: on Chrome, Firefox, and Edge, press Ctrl+Shift+Delete (Windows) or Command+Shift+Delete (Mac). Select "All time" and check the boxes for "Cookies and other site data" and "Cached images and files." Click "Clear data."

You can also set your browser to clear the cache automatically when you close it. On Chrome, go to Settings, click "Privacy and security," select "Clear browsing data," and check "Clear cookies and other site data when you quit Chrome." Firefox and Edge have similar options under their privacy settings.

Replace a traditional hard drive with a solid-state drive

If your computer is more than five years old and still has a traditional hard drive (you can check by opening Task Manager on Windows and looking at the disk usage — if it shows 100 percent for long periods, it is likely a traditional drive), replacing it with a solid-state drive (SSD) is the single biggest speed improvement you can make. An SSD has no moving parts and reads data 5 to 10 times faster than a traditional drive.

A 500-gigabyte SSD costs $40 to $60, and a 1-terabyte SSD costs $60 to $120. Installation takes 30 minutes to an hour if you do it yourself, or $50 to $100 if you take it to a repair shop. You will need to reinstall Windows or macOS on the new drive, which takes another 30 minutes.

Before you replace the drive, back up all your files. You can clone your old drive to the new one using free software like Macrium Reflect (Windows) or Disk Utility (Mac), which copies everything including your operating system and programs. This saves you from reinstalling everything.

Add more RAM if you use many programs at once

RAM (random-access memory) is the short-term memory your computer uses while programs are running. If you regularly have 30 or more browser tabs open, or you run heavy programs like video editing or 3D design software, adding RAM can help. Most computers come with 4 to 8 gigabytes; upgrading to 16 gigabytes costs $30 to $80 and takes 10 minutes if you do it yourself.

Check how much RAM you have and how much you are using: on Windows, open Task Manager and click the "Performance" tab, then "Memory." On Mac, open Activity Monitor (search for it), click the "Memory" tab, and look at "Memory Pressure." If the memory pressure is yellow or red most of the time, or if you are using more than 80 percent of your RAM, adding more will help. If you are using less than 50 percent, adding RAM will not make a noticeable difference.

Installing RAM is straightforward on most laptops and desktops, but some newer laptops have RAM soldered to the motherboard and cannot be upgraded. Check your computer's manual or search "[your model] RAM upgrade" before buying.

Frequently Asked Questions

Will updating Windows or macOS make my computer faster?

Updates usually do not make an older computer faster, but they fix security problems and bugs that can slow it down. Install updates when your computer prompts you. On Windows, go to Settings, click "Update & Security," and select "Check for updates." On Mac, go to System Settings, click "General," then "Software Update."

Should I use a cleaning tool or optimizer software?

Most optimizer software does not help much and some can cause problems. Stick with the built-in tools: Disk Cleanup on Windows, Storage management on Mac, and your browser's cache-clearing options. Malwarebytes is the one third-party tool worth using, and only for malware scans.

How often should I do these steps?

Disable startup programs once. Clear your browser cache monthly. Delete old files when your drive gets above 80 percent full. Run a malware scan every three months or if your computer suddenly feels slower. If you replace your hard drive with an SSD, you will not need to do much else for several years.

What if my computer is still slow after I do all of this?

If you have disabled startup programs, cleared files, scanned for malware, and your hard drive is not full, the problem is likely aging hardware. A computer more than seven years old may have a failing hard drive, degraded battery (on laptops), or straightforward components that are no longer fast enough. An SSD replacement is usually the best next step.

Is it safe to delete files from my Downloads folder?

Yes. Your Downloads folder is meant to be temporary storage. If you downloaded something you needed, you have already moved it or used it. Anything still there after a few weeks is safe to delete. The same goes for your Recycle Bin (Windows) or Trash (Mac) — emptying it frees up space.