Start with the fastest fixes first

A slow PC usually comes from one of three things: too many programs running at startup, a hard drive that is nearly full, or malware. Before you reinstall Windows or buy new hardware, restart your computer, check your disk space, and look at what is actually running. Most of the time one of these three fixes will bring your speed back.

The order matters. Restart first because it clears your RAM and stops temporary files from piling up. Then check how much free space you have left. Then look at startup programs. If none of those work, move to the malware and browser checks. This approach takes about 30 minutes and costs nothing.

Key Takeaways

  • Restart your PC, then check how much free disk space remains — if you have less than 10 percent free, delete old files or uninstall programs you do not use.
  • Open Task Manager (Ctrl+Shift+Esc on Windows, Activity Monitor on Mac) and look at the Startup tab to disable programs that launch when you turn on your computer.
  • Run Windows Defender (built into Windows) or a free malware scanner like Malwarebytes to check for infections that consume CPU and disk speed.
  • Clear your browser cache and check for unwanted extensions, which often slow down web browsing even when other programs run fine.
  • If slowness only happens during specific tasks like video editing or gaming, your RAM or graphics card may be the bottleneck, not a software problem.

Restart and check your disk space

Restart your computer. This clears your RAM, closes background processes that got stuck, and stops temporary files from building up. Wait for it to fully boot, then open File Explorer (Windows) or Finder (Mac) and look at your main drive. You need at least 10 percent of your total space free. If you have 500 GB total and only 30 GB free, you are at 6 percent — that is too low.

To free up space, delete old downloads, empty your Recycle Bin or Trash, and uninstall programs you no longer use. On Windows, go to Settings > Apps > Apps and Features, find programs you recognize, and click Uninstall. On Mac, open Applications, drag unused programs to Trash, and empty it. If you have large video or photo files you do not need, move them to an external drive or cloud storage.

Check your Downloads folder specifically — it often holds hundreds of old installers and files you forgot about. Sorting by date modified makes it straightforward to see what you have not touched in months.

Disable startup programs that slow your boot

Many programs set themselves to launch when you turn on your computer, and each one adds seconds to your startup time and consumes RAM while running. Open Task Manager on Windows by pressing Ctrl+Shift+Esc, then 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 need to run at startup — common culprits are Adobe Reader, Spotify, Discord, Dropbox, and antivirus software that is not Windows Defender. Select Disable. Do not disable anything labeled System or related to your keyboard, mouse, or graphics drivers. Restart your computer and you should notice faster boot times within a day or two.

On Mac, go to System Settings > General > Login Items, find programs in the list, select them, and click the minus button. The effect is the same: fewer things running in the background means faster startup and more RAM available for the programs you actually use.

Scan for malware and unwanted software

Malware and potentially unwanted programs (PUPs) consume CPU, disk, and bandwidth even when you are not using your computer. Windows comes with Windows Defender built in. Open Windows Security (search for it in the Start menu), click Virus and Threat Protection, then click Scan Options. Select Full Scan and run it. This takes 30 minutes to an hour but checks every file on your drive.

If you want a second opinion, read Malwarebytes Free from malwarebytes.com, install it, and run a scan. It catches things Defender sometimes misses, especially browser hijackers and adware. Do not pay for the premium version unless you want real-time scanning — the free version works fine for a one-time check.

After the scan finishes, restart your computer. If malware was found and removed, you should notice an when ready speed improvement because the malicious program is no longer running.

Clear your browser cache and remove unwanted extensions

If your PC feels fast but web browsing is slow, the problem is usually your browser, not your computer. Open your browser settings and clear your cache. In Chrome, go to Settings > Privacy and Security > Clear Browsing Data, select All Time, check Cookies and Other Site Data and Cached Images and Files, then click Clear Data. In Firefox, go to Settings > Privacy and Security, scroll to Cookies and Site Data, and click Clear Data.

Next, check your extensions. In Chrome, click the puzzle piece icon in the top right, then click Manage Extensions. Look for anything you do not recognize or remember installing — toolbars, coupon savers, and ad blockers you did not ask for are common slowdowns. Click the toggle to disable or remove them. In Firefox, go to Settings > Extensions and do the same.

Restart your browser. If you had five unwanted extensions, removing them can make web pages load noticeably faster because your browser is no longer running hidden scripts in the background.

Check if your RAM or hard drive is the real problem

If your PC is still slow after the steps above, the issue may be hardware rather than software. Open Task Manager (Ctrl+Shift+Esc on Windows) and click the Performance tab. Look at Memory and Disk. If Memory shows 90 percent or higher while you are just browsing, you do not have enough RAM — upgrading from 8 GB to 16 GB would help. If Disk shows 100 percent for long periods, your hard drive is the bottleneck.

Hard drives are slower than solid-state drives (SSDs). If your PC is more than five years old and still uses a traditional hard drive, replacing it with an SSD is one of the biggest speed improvements you can make. A 500 GB SSD costs between $40 and $70 and can be installed in 30 minutes if you are comfortable opening your computer, or by a technician for $50 to $100 in labor.

If slowness only happens during specific tasks — video editing, gaming, or running large spreadsheets — then RAM or your graphics card is the limiting factor, not a software problem. In that case, the fix is hardware, not the steps in this guide.

When to reinstall Windows or consider a factory reset

Reinstalling Windows is a last resort, not a first step. It erases everything on your drive, so back up your files first. Only do this if you have run all the steps above, found no malware, disabled startup programs, and your PC is still unusably slow.

On Windows 10 or 11, go to Settings > System > Recovery and click Reset This PC. Choose Keep My Files if you want to save your documents, or Remove Everything if you want a completely clean install. The process takes 30 minutes to an hour. On Mac, restart your computer, hold Command+R during startup to enter Recovery Mode, then choose Reinstall macOS.

Before you do this, make sure your files are backed up to an external drive or cloud service like OneDrive, Google Drive, or iCloud. A fresh install often does speed up an old PC, but only because you are removing years of accumulated software and settings — the same effect you can get by following the steps above.

Frequently Asked Questions

Why is my PC slow even after restarting?

Restart clears RAM but does not fix the underlying cause. Check your disk space, look at Task Manager to see what is using CPU, and scan for malware. One of those three is usually the culprit. If all three are fine, your hard drive may be failing or your RAM may be full.

Is it safe to disable programs in the Startup tab?

Yes, as long as you do not disable anything labeled System or related to your hardware drivers. Programs like Spotify, Discord, and Adobe Reader are safe to disable. If you disable something and your computer stops working right, go back to Task Manager and re-enable it.

How often should I clear my browser cache?

Clearing cache once a month is enough for most people. If you browse a lot and notice slowness, clear it every two weeks. Clearing cache does not hurt anything — it just frees up disk space and can speed up your browser.

Does upgrading to an SSD really make a big difference?

Yes. If you have a traditional hard drive, upgrading to an SSD is one of the biggest speed improvements you can make. Boot time drops from 60 seconds to 15 seconds, and programs launch much faster. It is worth the cost if your PC is more than five years old.

What if none of these steps work?

If your PC is still slow after checking disk space, disabling startup programs, scanning for malware, and clearing your browser, the problem is likely hardware — a failing hard drive, not enough RAM, or an old processor. Take your computer to a technician for diagnosis, or consider whether it is time to replace it.