What's Making Your PC Slow and How to Fix It

A slow PC usually comes from one of four things: too many programs running at startup, a hard drive that's nearly full, malware or unwanted software, or a hard drive that's failing. You can fix the first three yourself in an hour or two. The fourth requires a professional or a new drive.

Start by checking how much free space you have on your main drive, what's running in the background, and whether your system is infected. Most slowdowns come from programs you installed months ago that now launch every time you start Windows or Mac, eating memory and processing power before you even open a browser.

Key Takeaways

  • Disable startup programs through Task Manager (Windows) or Activity Monitor (Mac) to free up memory and speed up boot time.
  • Delete or move large files, uninstall unused programs, and empty your Recycle Bin to free up at least 10 percent of your drive's total space.
  • Run a malware scan with Windows Defender (built into Windows) or a free tool like Malwarebytes to catch unwanted software.
  • If your PC is more than five years old and still uses a traditional hard drive, replacing it with a solid-state drive (SSD) will make the biggest difference in speed.
  • Restart your PC regularly—at least once a week—to clear memory and stop background processes from accumulating.

Stop Programs From Running at Startup

Every program you install asks Windows or Mac for permission to launch automatically when you start your computer. Most of them you never use, but they load anyway, consuming memory and slowing your boot time. Disabling these is the fastest fix you can make.

On Windows: Press Ctrl+Shift+Esc to open Task Manager. Click the "Startup" tab. You'll see a list of programs with a "Status" column showing "Enabled" or "Disabled". Right-click any program you don't need at startup—Spotify, Discord, Adobe Reader, printer software—and select "Disable". You won't lose the program; it just won't launch automatically. Restart your PC to see the difference.

On Mac: Go to System Settings, then General, then Login Items. You'll see two lists: "Allow in the Login Window" and "Open at Login". Select any app in the second list and click the minus button to remove it. Again, the app stays installed; it just won't open when you start your Mac.

If you're unsure whether a startup program is safe to disable, search its name online. Most common ones—Spotify, Discord, OneDrive, Dropbox—are safe to turn off. If you disable something and your PC breaks, you can always turn it back on.

Free Up Space on Your Hard Drive

When your drive is more than 90 percent full, Windows and Mac slow down because they need free space to write temporary files and run programs. Aim to keep at least 10 percent of your drive empty.

Check how much space you're using. On Windows, right-click your C: drive in File Explorer, select Properties, and look at the pie chart. On Mac, click the Apple menu, select About This Mac, then Storage. If you're above 90 percent, you need to delete or move files.

Start by emptying your Downloads folder—most people accumulate months of installers and documents there. Move anything you want to keep to an external drive or cloud storage like OneDrive, Google Drive, or iCloud. Then delete the rest. Empty your Recycle Bin (Windows) or Trash (Mac) afterward; deleted files still take up space until the bin is emptied.

Next, uninstall programs you don't use. On Windows, go to Settings > Apps > Apps & Features, find programs you recognize but don't open, and click Uninstall. On Mac, open Applications in Finder, select unused apps, and drag them to Trash. This frees up space and removes startup programs at the same time.

Scan for Malware and Unwanted Software

Malware and adware slow your PC by running hidden processes, displaying ads, and hijacking your browser. Windows comes with Windows Defender, a built-in antivirus that runs automatically. You can also run a manual scan.

On Windows, click the Start menu, type "Windows Security", and open it. Click "Virus & threat protection", then "Scan options". Select "Full scan" and click "Scan now". This takes 30 minutes to an hour but checks every file on your drive. Let it finish, and remove anything it finds.

On Mac, Apple's built-in protections are less visible but still active. If you suspect malware, read the free version of Malwarebytes from malwarebytes.com, install it, and run a scan. Mac malware is less common than Windows malware, but it exists.

If a scan finds nothing but your PC is still slow, you may have adware or browser hijacker software that doesn't trigger antivirus alerts. Look at your browser's homepage and search engine. If they've changed to something unfamiliar, go to your browser settings and change them back. Then uninstall any browser extensions you don't recognize.

Upgrade to a Solid-State Drive If Your PC Is Old

If your PC is more than five years old and still uses a traditional hard drive (not an SSD), replacing it is the single biggest speed improvement you can make. A hard drive with moving parts reads data slowly compared to an SSD, which has no moving parts.

You can tell what you have by opening Settings (Windows) or System Report (Mac) and looking for the drive type. If it says "HDD" or "Hard Disk Drive", you have a traditional drive. If it says "SSD" or "Solid State Drive", you already have the faster type.

Replacing a hard drive requires opening your PC or Mac, which is straightforward on a desktop but harder on a laptop. If you're not comfortable doing it yourself, a computer repair shop can do it for $100 to $300 including the drive. The speed difference is dramatic—boot time drops from two minutes to 20 seconds, and programs open when ready instead of taking 10 seconds.

Before you replace the drive, back up your files to an external drive or cloud storage. You'll need to reinstall Windows or Mac on the new drive, which the repair shop can do, or you can do it yourself using a USB installer from Microsoft or Apple.

Adjust Visual Effects and Background Processes

Windows and Mac both run visual effects—animations, shadows, transparency—that look nice but consume processing power on older PCs. Turning them off won't make your PC beautiful, but it will make it faster.

On Windows: Right-click "This PC" or "My Computer" on your desktop, select Properties, then click "Advanced system settings" on the left. Under the "Performance" section, click "Settings". Select "Adjust for best performance" to turn off all visual effects at once. If you want to keep some effects, select "Custom" and uncheck the ones you don't need.

On Mac: Go to System Settings > General > Accessibility > Display. Turn on "Reduce motion" and "Increase contrast" if you want. These changes are smaller than on Windows, but they help.

You can also limit background app refresh. On Windows, go to Settings > Privacy & Security > App permissions > Background apps and turn off apps you don't need running in the background. On Mac, go to System Settings > General > Login Items and remove apps from the "Allow in the Login Window" section.

Restart Your PC Regularly

Restarting clears your computer's memory and stops background processes from accumulating. A PC that hasn't been restarted in weeks will be noticeably slower than one restarted weekly.

Set a reminder to restart your PC at least once a week, ideally on Sunday evening or Monday morning. If you leave your PC on 24/7, you're letting memory leaks and stuck processes build up. A five-minute restart takes almost no time and pays off in speed.

When to Call a Professional or Replace Your PC

If you've disabled startup programs, freed up drive space, scanned for malware, and your PC is still slow, the problem is likely hardware failure. A failing hard drive, bad RAM, or overheating CPU requires professional diagnosis.

Take your PC to a local repair shop and describe what you've already tried. They can run diagnostic tests in 30 minutes and tell you whether the drive is failing, RAM is bad, or the CPU is overheating. Repairs usually cost $100 to $300. If your PC is more than seven years old, replacement may be cheaper than repair.

If your PC is still under warranty, contact the manufacturer's support line before paying for repairs. Dell, HP, Lenovo, and Apple all offer mail-in or on-site repair for machines still covered.

Frequently Asked Questions

How long does it take to see a speed improvement after disabling startup programs?

You'll see the biggest difference in boot time—how long it takes to start your PC—which should drop by 30 to 60 seconds if you disabled several programs. Restart your PC to see the change. Overall responsiveness improves when ready, but the effect is most noticeable when you first turn on your computer.

Is it safe to delete files from my Downloads folder?

Yes, if you've already moved anything you want to keep. The Downloads folder is meant to be temporary. Installers for programs you've already installed can be deleted safely. If you're unsure whether you need a file, move it to an external drive first, then delete it from your PC after a month.

Will turning off visual effects make my PC look bad?

Yes, slightly. Animations and transparency effects disappear, and the interface looks flatter. On older PCs, the speed gain is worth it. On newer PCs, you can keep the effects on without noticing slowness. Try it for a day; if you hate it, you can turn the effects back on in the same menu.

How much does an SSD cost and how long does installation take?

A 500GB SSD costs $40 to $60, and a 1TB SSD costs $60 to $100. Installation by a repair shop takes one to two hours plus the cost of labor, usually $100 to $200. If you do it yourself, it takes 30 minutes on a desktop but can be difficult on a laptop. The speed improvement justifies the cost on any PC more than five years old.

What's the difference between restarting and shutting down?

Restarting closes all programs and clears memory, then starts fresh. Shutting down does the same but leaves the PC off. Both clear memory, but restarting is faster if you want to use your PC again when ready. Sleep mode does not clear memory, so a PC in sleep for weeks will still be slow when you wake it.