Tech guide

Why Is My Computer So Slow?

By the FixlyDesk team · Published November 1, 2026

A slow computer is a symptom, not a diagnosis. The same sluggishness can come from a program hogging the processor, a drive that is nearly full, an update running in the background, a browser loaded with extensions, malware, or hardware that is wearing out.

The steps below start with the quick, reversible checks that solve a lot of cases, then move on to the signs that point to something more serious. They cover Windows and Mac; menu names can differ slightly between versions.

Before you start

Back up anything you can't afford to lose

If your important files are not already backed up, copy them to an external drive or a cloud service before you change anything. This matters most if the computer is also freezing, crashing, or making clicking or grinding noises — those can be early signs of a failing drive, and in that case backing up comes before every other step.

Notice when it slows down

Before changing anything, spend a day paying attention to when the slowness happens. The pattern usually points to the cause, and it tells you which of the steps below to start with.

Slow for the first few minutes after you turn it on, then fine

Too many programs starting at once, or updates catching up in the background. Start with cutting down startup programs.

Slow all the time, from the moment it starts

Look at storage space, malware, and the hardware signs further down — a nearly full drive, too little memory or an older hard drive.

Fine after a restart, but slower the longer it stays on

A program that keeps using more memory, a pile-up of browser tabs, or the computer getting hot. Check what's using it in Task Manager or Activity Monitor.

Only slow in one program

That program is the likely cause rather than the whole computer. Update it, restart it, and check whether it's doing something heavy like syncing or scanning.

It started suddenly after an update or a new install

That change is the first suspect. Let any update finish completely, and uninstall a new program you don't need to see whether things recover.

Only websites are slow

It may not be the computer at all — see "Is it the computer, the website or the internet?" below.

Quick checks to try first

Restart, don't just shut down
On Windows, choose Restart rather than Shut down. Windows' Fast Startup feature means a shutdown doesn't always clear everything the way a restart does. On a Mac, use the Apple menu and choose Restart. If the computer hasn't been restarted in days or weeks, this alone can make a noticeable difference.
See what is actually using the computer
On Windows, press Ctrl + Shift + Esc to open Task Manager and sort by CPU, Memory and Disk. On a Mac, open Activity Monitor from Applications › Utilities. Look for one program sitting near the top of the list the whole time, memory that is almost completely used, or a disk that stays at 100% even when you aren't doing anything.
Close what you don't need
Quit programs you aren't using rather than leaving them minimized. Web browsers are often the biggest consumer of memory — dozens of open tabs can slow down an otherwise healthy machine.
Cut down startup programs
Many programs set themselves to launch every time you sign in. On Windows, open Task Manager and go to Startup apps; on a Mac, go to System Settings › General › Login Items. Turning an item off here is reversible — it just stops it opening automatically. Leave security software alone, and look up anything you don't recognize before switching it off.

Check your storage space

A drive that is nearly full slows almost everything down, because the operating system needs free space to work with. On Windows, go to Settings › System › Storage. On a Mac, go to System Settings › General › Storage (on older versions, Apple menu › About This Mac › Storage).

Empty the Recycle Bin or Trash.
Clear out the Downloads folder — it often holds installers and files you only needed once.
Uninstall programs you no longer use, through Settings › Apps on Windows or by removing them from Applications on a Mac.
Move large photo and video collections to an external drive or cloud storage, once you have confirmed the copy worked.

Skip the "PC cleaner" downloads

Programs that promise to speed up your computer, clean the registry or update all your drivers are rarely needed, and some come bundled with adware. The built-in tools above do the same job safely.

Let updates finish

Operating system and app updates often download and install in the background, and a computer can feel slow while that is happening. Check Windows Update in Settings, or Software Update in System Settings on a Mac, and let anything pending finish and restart.

Don't power off during an update

If the screen says an update is installing, leave it plugged in and let it finish. Cutting the power part-way through an update can leave a computer unable to start.

Is it the computer, the website or the internet?

When pages take ages to load, it's easy to blame the computer when the problem is somewhere else. A couple of quick comparisons usually settle it.

One website or app is slow, but others are fine

The problem is most likely that website or service, not your computer. Try again later — many services publish a status page that shows when they're having trouble.

Every website is slow on this computer, but fine on a phone using the same Wi-Fi

It's the computer or its browser. Try a different browser: if that's quick, the first browser is the cause.

Websites are slow on every device in the house

It's the internet connection or the router, not the computer. Our Wi-Fi guide covers how to narrow that down.

Everything on the computer is slow, not just websites

It's the computer itself. Carry on with the steps in this guide.

If it's the browser, close tabs you don't need, make sure the browser is up to date, and review its extensions or add-ons. Remove any you don't recognize or no longer use — unfamiliar extensions can slow browsing down and are a common way for adware to get in.

Rule out malware

Malware can use a lot of processing power without showing anything on screen. Warning signs include pop-ups, a browser homepage or search engine that changed on its own, unfamiliar programs, or the computer working hard while idle.

On Windows, open Windows Security › Virus & threat protection › Scan options and run a Full scan with Microsoft Defender. Run one security product at a time — installing two antivirus programs at once can make a computer slower, not safer.

Signs it's the hardware

Clicking or grinding noises, frequent freezing, or a disk stuck at 100% for long stretches

The drive may be failing. Back up now and avoid heavy use until it has been checked.

Loud fans, a hot case, and slowdowns that get worse the longer you use it

The computer may be overheating. Keep vents clear, use a laptop on a hard surface rather than a bed or couch, and have dust cleaned out if it's been years.

An older computer with a traditional spinning hard drive

The drive itself is often the bottleneck. Replacing it with a solid-state drive (SSD) can make an older machine feel much faster, but it involves copying your system and files across, so it's worth having done carefully.

Memory is almost always full, even with only a few programs open

The computer may not have enough memory (RAM) for how you use it. Some computers can be upgraded; others can't.

What not to do

Don't reach for a factory reset as the first fix. It erases your programs and settings, and often your files, and it doesn't help if the cause is hardware.
Don't delete files from system folders you don't recognize.
Don't call a phone number from a pop-up that says your computer is infected. Legitimate companies don't contact you that way.

When to get professional help

It's worth bringing in a technician if the computer makes unusual noises, crashes or shows blue screens, is still slow after the steps above, shows signs of infection, or holds files you can't risk losing. The same goes for upgrades such as moving to a solid-state drive or adding memory, where your data has to be moved across safely.

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