Slow computer? Causes and safe fixes you can try
A slow computer is one of the most common things people ask me about. The good news is that a lot of slowness has ordinary causes you can check yourself without spending money. These steps are safe on both Windows and Mac. Work through them in order and stop when things improve.
Written by Adam CurtisPublished Last updated
Before you start: back up anything important
None of these steps should delete your files, but a slow computer is sometimes an early sign of a failing drive. If you have photos or documents you'd hate to lose, copy them to an external drive or cloud storage first. It takes a few minutes and removes the worry.
Step 1: Restart properly
On Windows, choosing Shut down doesn't always fully reset the system, because of a feature called fast startup. Choosing Restart does. If your computer hasn't been restarted in days or weeks, do that first.
On a Mac, choose Restart from the Apple menu. It sounds too simple, but it clears out programs that have been slowly using more memory over time.
Step 2: Install updates
Updates fix bugs and security problems, and sometimes the slowness itself. On Windows, go to Settings, then Windows Update. On a Mac, go to System Settings, General, then Software Update. Let them finish and restart when asked.
Updates can make a computer slow for a while as they install. If it's slow straight after an update, give it a restart and some time before judging.
Step 3: Check your storage space
A nearly full drive slows everything down. On Windows, open Settings, System, then Storage. On a Mac, open System Settings, General, then Storage.
As a rough guide, try to keep at least 10 to 15 percent free. The usual culprits are the Downloads folder, old videos and duplicate photos. Move them to an external drive or cloud storage rather than deleting anything you're unsure about. If cloud storage is part of the mess, cloud and file support can help sort it out.
Step 4: See what's using the computer
Both systems have a built-in tool that shows what's running:
- Windows: press Ctrl + Shift + Esc to open Task Manager. Click the CPU or Memory column to sort by what's using the most.
- Mac: open Activity Monitor from Applications, then Utilities, and sort by CPU or Memory.
Programs you recognise using a lot, like a browser with many tabs, are normal. Something unfamiliar near the top is worth looking up before you do anything with it.
Then check what starts automatically. On Windows, use the Startup apps tab in Task Manager. On a Mac, go to System Settings, General, then Login Items. Turning off apps you don't need at startup is safe and often helps a lot.
Step 5: Look at your browser
For many people, the browser is the computer. Dozens of open tabs use a lot of memory. Close what you don't need and bookmark the rest.
Then check the browser's extensions or add-ons and remove any you don't recognise or no longer use. Unwanted extensions are a common cause of slowness, pop-ups and changed search engines.
Step 6: Run a security scan
On Windows, open Windows Security from the Start menu and run a quick scan with the built-in Microsoft Defender. Macs have built-in protection that runs in the background. If you're seeing pop-ups, changed browser settings or programs you didn't install, that's a sign to get computer security help.
What not to do
- Don't download “cleaner”, “booster” or registry cleaning programs, especially ones advertised by pop-ups.
- Don't call a phone number that appears in a warning on screen.
- Don't delete files from system folders to free up space.
- Don't buy a new computer until you know what's actually causing the problem.
When a remote session helps, and when it doesn't
If you've worked through these steps and it's still slow, a remote session can dig deeper: startup items, background services, software conflicts, update problems or unwanted programs. My slow computer help page explains what I check, and it works the same way for Windows and Mac computers.
Some causes are physical. A computer that's very noisy, overheating, clicking, or still using an old spinning hard drive may need hardware work. I don't do house calls or repairs, so I'll tell you honestly if that's where it's heading and suggest taking it to a local repairer. You can read more on Apple's or Microsoft's own support sites, such as Microsoft Support (opens in a new tab).
Common questions
Will more memory (RAM) fix my slow computer?
Sometimes, if memory is actually the bottleneck. Adding RAM is physical work for a local repairer, and some laptops can't be upgraded at all. In a remote session I can check whether memory is the real problem first, so you don't pay for an upgrade that doesn't help.
Are free PC cleaner programs safe to use?
Many aren't worth the risk. Some bundle unwanted software or show scary results to sell you a paid version. Windows and macOS include the tools most people need. Avoid anything offered by a pop-up.
Is it worth fixing an old computer?
It depends on its age and whether it still gets security updates. If it does, a clean-up and some sensible changes can make it usable again. If it no longer gets updates, I'll tell you honestly that replacing it is probably the better option.
How much does slow computer help cost?
Remote support is $89 per hour with a one hour minimum, then 15 minute blocks. I'll tell you before going past the first hour. No fix, no fee applies if I can't make meaningful progress on the agreed issue.