Why Is My Computer So Slow? Common Causes and Fixes
A slow computer is frustrating, but most cases have a straightforward cause. This guide walks through the most common reasons and practical fixes you can try today.
At a Glance
Restart the computer with a full shutdown
~42sQuick Tip
Quick Tip: If your computer feels slow and you cannot remember the last time you shut it all the way down — not just closed the lid — start here. A full shutdown once a week is a good habit.
Disable unnecessary startup programs (Windows)
~27sFree up storage space by clearing clutter
~43sWarning
Only delete files you are certain you no longer need. When in doubt, leave it. Deleting system files or program files can cause problems — stick to your personal files in Downloads, Documents, and Desktop.
Run a malware scan
~27sCheck if it is time for a hardware upgrade or new computer
~39sYou Did It!
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A computer that was fast when you bought it and is now slow did not break — it got bogged down. In most cases, the slowdown has a specific cause that can be identified and fixed without buying a new machine.
The four most common culprits are: too many programs starting up automatically when the computer turns on, running out of available storage space on the drive, a malware infection, and hardware that is aging or underpowered for what you are asking it to do.
The startup programs issue is extremely common. Every time you install a new app, it often adds itself to the list of programs that launch automatically when Windows or macOS starts. Over time, this list can grow to dozens of programs all loading at once when you turn on the computer, each using memory and processing power. Trimming this list is one of the fastest improvements you can make.
Low storage space causes slowdowns because the operating system uses free space on your drive as temporary workspace. When the drive gets too full — generally below 10 to 15 percent free space — the computer runs out of room to work and slows significantly. On a 500 GB drive, that means keeping at least 50 to 75 GB free. Large culprits are usually the Downloads folder, large video files, old program installers, and the Recycle Bin (Windows) or Trash (Mac).
Malware — malicious software that has been installed without your knowledge — can consume processor power and memory in the background while hiding from you. Running a trusted security scan is worth doing if your computer has become suddenly and inexplicably slow.
One more fix many people overlook: a true full shutdown and restart. Many people put their computers to sleep rather than shutting them all the way down. A full shutdown clears temporary files, reloads the operating system fresh, and applies any pending updates. If your computer has not been fully restarted in weeks, doing so often produces a noticeable improvement.
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