Skip to main content
  • 1-Click Updates All Your Software
  • Faster Computer
  • Safer Browsing
  • Fewer Errors & Crashes
  • Quicker Startup

Get a cleaner, faster, and smoother-running PC with CCleaner

CCleaner has been downloaded over 2.5 billion times!

Start Free Scan

No credit card needed — just install and go

No credit card needed - just install and go Start Free Scan

Computer running slow?

There are a number of possible reasons that your computer is running slow and while you might be keen to understand exactly why, it isn’t always clear if your computer is suffering from just one or multiple issues. For Windows computers, there are a few typical reasons for lagging performance and your PC’s problem could be one of the following:

Your computer has run out of hard drive space

There are a few ways of finding this information depending which version of Windows you are using, but you can check your computer’s spec for free by downloading Speccy. If your computer’s hard drive is full, you should delete any unused programs to free up some space. You can do this quickly and easily using CCleaner’s uninstall tool, which can be found by clicking ‘Tools’ > ‘Uninstall’. It provides a list of installed apps by file size so you can delete items wasting most space first.

Your computer is clogged up with old cache and temporary files

Every time you use your computer it collects these files and if they’re not deleted, they can build up over time until they affect your PC’s performance. As well as using up space on your computer, these files can present a significant security risk in some situations. For example, Windows and many other programs will create lists of ‘recently used files’ to log your recent activities. This can be convenient for you if you want to retrace your steps. However, this information is valuable to hackers if malicious software is planted on your PC. Your computer doesn’t need these files and CCleaner can quickly, easily and safely delete them for you.

You have missed Windows updates or have outdated drivers

Although those reminders to update might seem like a pain, they exist for a valuable reason. Your PC needs to be kept up to date to ensure that it can perform normally, and that you are protected from malicious activities. Update reminders include those from Windows and from any installed software. To make the job of keeping up to date a bit easier, CCleaner has a built-in Software Updater tool, to update your apps in one go.


  • Why is my Windows 10 running slow?

    Every version of Windows has quirks. Windows 10 is no different. There are many factors that slow down this operating system, including insufficient RAM, full hard drives, performance settings, irregular updates and more.

  • How do you fix a slow computer?

    Getting a slow PC fixed partly depends on its specs and operating system. More than this, you need to understand what kinds of problems impact all computers, such as full hard drives, viruses and malware and more.