When a computer slows down, the cause might be one busy app, too many programs launching at sign-in, low storage, or a problem that needs repair. Work through the reversible checks below before buying utilities, deleting files, or resetting the computer. The steps cover Windows and macOS.
If the computer is reporting storage errors, repeatedly freezing, or behaving as if its drive may be failing, back up important files before troubleshooting. For a work computer, confirm that the backup or cloud sync has actually completed.
1. Restart and narrow down the problem
Save your work and choose Restart rather than leaving the computer asleep. Once it starts again, check whether the whole computer is slow or just one app or website. Note when the slowdown happens, such as after sign-in or while a particular task is running. That helps narrow the cause without changing settings at random.
If only one app is affected, update or restart that app and check its own help resources before changing system settings.
2. See what is using system resources
On Windows, press Ctrl + Shift + Esc to open Task Manager. On a Mac, open Activity Monitor from Applications > Utilities. Sort the process list by CPU or memory use and look for an app you recognize that is using a lot while the computer feels slow. Apple's Activity Monitor User Guide explains the information shown there.
Close an app you started if you no longer need it. Do not force-quit unfamiliar system processes just because their names are unclear; check the app or operating-system documentation first. Many open browser tabs can also use memory, so close tabs you are finished with rather than relying on a tab count as a diagnosis.
3. Review apps that open at sign-in
Background apps can use resources even when you are not actively working in them. Disable only the startup or login items you recognize and do not need immediately; leave backup, security, and other essential apps enabled.
- Windows: Open Settings > Apps > Startup, or review startup apps in Task Manager.
- macOS: Open System Settings > General > Login Items & Extensions and review what opens at login.
Microsoft's guide to configuring startup apps in Windows and Apple's guide to login items on Mac explain these controls.
4. Install trusted updates
Install operating-system and app updates from their built-in settings or the software maker, then restart if prompted. Keep security updates enabled: turning them off can leave the computer exposed and is not a safe performance fix. Avoid third-party driver-updater or registry-cleaner apps that promise to speed everything up.
5. Check available storage before deleting anything
Review storage in Settings > System > Storage on Windows or System Settings > General > Storage on macOS. If space is tight, remove files you recognize, uninstall apps you no longer use, or move large personal files to a verified backup. Check the Recycle Bin or Trash before emptying it.
Use the operating system's storage tools, and review what they are set to remove. In particular, do not enable automatic deletion of your Downloads folder unless you are comfortable with files there being removed. Microsoft's Windows storage guide and Apple's Mac storage guide describe the built-in options.
6. Check for unwanted software
On Windows, open Windows Security > Virus & threat protection and run a scan. If you still suspect malware, use the scan options in Windows Security and follow Microsoft's guidance; do not download a scanner from a pop-up or an unsolicited message. See Microsoft's Windows Security overview.
On a Mac, install macOS security updates and review recently installed apps and login items. If a warning or suspicious behavior persists, consult Apple Support or a trusted technician instead of installing an unverified "cleaner."
7. Know when to stop and get help
If the computer remains slow after these checks, note any error messages and recent changes, and back up your files before trying more disruptive repairs. Repeated crashes, disk errors, or abnormal heat can point to a hardware or system problem that routine cleanup will not fix. A repair professional can check the device and explain whether a repair or compatible memory or storage upgrade is worthwhile.
Before reinstalling an operating system or resetting the computer, make and verify a current backup and check the manufacturer's recovery instructions. A reset can remove apps and personal data.
For more practical technology tips, explore the rest of Super Dev Resources.
