How to Clean Up and Speed Up a Slow Computer (Windows and Mac)

Your computer used to feel snappy. Now it feels like it’s wading through mud, every click followed by a pause, every app opening with a sigh. It’s frustrating, and it steals time in tiny, constant bites.

The good news is that most slow computers don’t need magic, they need basic housekeeping. The biggest speed gains usually come from freeing storage, trimming what starts up in the background, removing malware, and sorting out heat.

Start with one quick win: restart your computer. Then work through the checklist below in order. You’ll fix the common causes first, and you’ll avoid deleting things you’ll regret later.

Spot the real reason your computer is slow (before you delete anything)

Guessing wastes time. A slow computer is usually one of these problems:

• Storage is nearly full: saving files feels sluggish, updates fail, apps stall.
• Too many apps running: the system feels “busy” even when you’re doing little.
• CPU stuck high: fans ramp up, everything lags, video calls glitch.
• Memory is strained: switching between tabs stutters, apps reload.
• Overheating: it gets hot, fans roar, performance drops.
• Old hardware: it’s “clean”, but still slow, especially on older hard drives.

This section is about getting a quick read on what’s happening right now, so your clean-up is targeted.

Do a 3-minute speed check: storage, memory, CPU, and heat

You don’t need specialist tools. Use what’s already built in.

A simple rule that helps most people: aim for about 20% free storage. When a drive is crammed full, your computer has less breathing room for temporary files, updates, and caching. It’s like trying to cook in a kitchen where every surface is already covered.

Also take note of heat. If it sounds like a hairdryer when you’ve only got a browser open, heat or a runaway process is likely involved.

Know the difference between a quick fix and a real fix

Some actions help today:

• Restarting
• Closing heavy apps
• Reducing tabs

They’re useful, but the slowness often returns because the cause is still there.

Real fixes tend to be boring, and that’s why they work:

• Freeing storage space
• Trimming startup apps
• Uninstalling unused software
• Running malware checks
• Cooling a dusty machine
• Installing updates

Be friendly with your future self: avoid random “speed booster” downloads. Many are aggressive cleaners, adware, or both. Stick to built-in tools and reputable sources. Microsoft’s own guidance covers safe basics for Windows performance without sketchy extras: https://support.microsoft.com/en-gb/windows/tips-to-improve-pc-performance-in-windows-b3b3ef5b-5953-fb6a-2528-4bbed82fba96

Clean up your storage safely (free space, reduce clutter, speed up tasks)

When storage is tight, your computer can feel slow even if it’s not “broken”. Searches take longer, installs hang, and the system struggles to shuffle files around.

Before you delete anything big, back up what matters. If you’re not sure what’s important, copy your photos and key documents to an external drive or a trusted cloud folder first.

Also, don’t forget the obvious: empty the Recycle Bin (Windows) or Trash (Mac). People often “delete” gigabytes, then keep them sitting in the bin for months.

Delete the space hogs first: downloads, videos, duplicate files, and old installers

Start with the biggest wins. You’re not trying to polish every pebble, you’re moving the boulders.

A simple process that works on both Windows and Mac:

1. Sort files by size in your main folders (Downloads, Desktop, Documents).
2. Make a single folder called Keep and move anything you’re unsure about into it.
3. Remove obvious clutter: old installers, duplicated downloads, outdated ZIP files.
4. Uninstall games you don’t play and creative apps you no longer use.
5. Move large personal videos and photo archives to an external drive or cloud.

Downloads is usually a goldmine of forgotten clutter. It often holds years of installers, duplicate PDFs, and five copies of the same photo someone sent on WhatsApp.

If you want extra ideas for older Windows PCs, this roundup is a useful reference point for safe, reputable helpers (read it as a guide, not a shopping list): https://www.slashgear.com/2065210/apps-speed-up-old-windows-pc/

Clear system junk the safe way (Disk Cleanup on Windows, Storage on Mac)

Once the big files are handled, clear system junk using built-in tools. This is where you get free space without risking important files.

Windows (safe approach)

• Search for Disk Cleanup, select your drive, then tick items like temporary files and Recycle Bin.
• In Windows 11, also use Storage Sense (Settings, System, Storage). It can automatically clear temporary files over time.

Mac (safe approach)

• Go to Apple menu, About This Mac, Storage, then Manage.
• Empty Trash.
• Use the built-in recommendations like Optimise Storage if it fits how you work.

Avoid manually deleting system folders you don’t recognise. If a folder name looks important, it probably is.

A light routine helps more than a once-a-year panic clean. Ten minutes weekly, or half an hour monthly, keeps storage from quietly filling up again.

Stop slow boot and lag by trimming startup apps and background tasks

Startup clutter is like leaving every tap running. Each app might only sip a bit of memory or CPU, but together they drain the system before you even open what you need.

The goal is not to remove everything. Keep what protects the system or makes hardware work properly, then cut the “nice-to-have” extras.

Disable startup apps you don’t need (Windows and Mac steps)

Windows

• Press Ctrl + Shift + Esc to open Task Manager.
• Go to Startup.
• Disable non-essential items like chat apps, game launchers, update helpers, and “quick start” tools you rarely use.

Mac

• Open System Settings, General, Login Items.
• Remove anything you don’t need on every boot.

A small, sensible “keep” list:

• Security tools you trust
• Touchpad, audio, and graphics drivers (or their control panels)
• Password manager (if you rely on it daily)

After trimming startup apps, restart once and feel the difference. Boot time is often the first thing that improves.

Uninstall apps you no longer use (and remove browser add-ons too)

Some apps don’t just sit there. They add background services, update schedulers, and menu bar helpers. Uninstalling unused software can reduce lag, stop pop-ups, and cut boot time.

Also check your browser. Extensions can slow page loads, increase memory use, and sometimes hijack your search settings.

Do a quick browser clean-up:

• Remove extensions you don’t recognise or don’t use.
• Delete toolbars and “shopping helpers”.
• If your homepage or search engine changed on its own, set it back.

One more practical tip: too many tabs can crush older machines. If you keep dozens open “just in case”, bookmark a few and close the rest. Your computer shouldn’t have to hold your entire brain in RAM.

Fix the big hidden drains: malware, updates, and overheating

This is the deep clean that often brings the biggest lift, especially if the slowdown started suddenly.

You’re aiming for three outcomes:

• Nothing nasty is running in the background
• The system is patched and stable
• The hardware isn’t throttling itself because it’s too hot

Run a proper malware scan and remove threats

Malware doesn’t always announce itself. Sometimes it just makes everything slow while it does its own thing.

Windows

• Open Windows Security and run a Full scan.
• If you want a second opinion, Malwarebytes is a common choice for on-demand scanning.

Mac
Macs have strong built-in protections, but a scan can still help if you’re seeing pop-ups, strange browser behaviour, or unknown apps.

Watch for red flags:

• Fans loud while you’re doing almost nothing
• Browser redirects or new tabs opening on their own
• New “security” apps you didn’t install
• Sudden waves of ads across websites that used to be clean

If you find something, remove it, restart, then re-check Task Manager or Activity Monitor to see if CPU use calms down.

Update your system, drivers, and apps, then check power settings

Updates can feel like a chore, but they fix bugs and can improve performance. They also close holes that malware uses.

Windows

• Run Windows Update and install optional driver updates if offered.
• If games, video playback, or graphics work feels slow, update your graphics driver from the maker (NVIDIA, AMD, or Intel).
• Check power mode. On desktops, or when a laptop is plugged in, a higher performance mode can help.

Mac

• Go to System Settings, General, Software Update.
• Update key apps too, especially browsers.
• Check Battery settings when plugged in, since low power settings can reduce performance.

For broader consumer-friendly guidance on speeding up tech in general, including computers, Which? keeps advice grounded and practical: https://www.which.co.uk/news/article/how-to-speed-up-everything-a3tVv0f101lD

Cool it down: dust, fans, and heat slow computers more than people think

Heat is a silent handbrake. When a computer gets too hot, it protects itself by slowing down. You can have plenty of storage and still get lag if the machine is cooking inside.

Safe cooling steps:

• Power off and unplug (and remove the laptop charger).
• Use compressed air in short bursts around vents.
• Don’t spin fans wildly with air blasts. Hold them still if you can reach them safely.
• Keep vents clear. Soft beds and sofas can block airflow fast.
• Use a hard surface for laptops, and consider a simple stand if it runs hot.

A blunt guideline: if it’s too hot to keep your hand near the vent for long, it needs attention.

If you’re on a Mac and want a Mac-specific checklist for getting speed back, this guide covers sensible steps and also explains why memory and storage matter: https://uk.crucial.com/articles/mac-users/how-to-speed-up-your-mac-system

When cleaning isn’t enough: simple upgrades that make an old PC feel new

Sometimes your computer is slow because it’s reached its limit. That doesn’t mean you need a brand-new machine. Two upgrades often change the whole feel of a PC (and some Macs), even on a budget: an SSD and more RAM.

This section is about spotting when cleaning has done all it can.

Upgrade to an SSD for the biggest speed boost

If your computer still uses an old spinning hard drive (HDD), switching to an SSD is the single biggest speed improvement you can make.

What you’ll notice:

• Faster boot times
• Apps opening quickly
• Less waiting when copying files
• Smoother updates

You can clone your old drive onto the new SSD, or do a fresh install if you want a clean start. Back up first either way.

If you’re using a Mac and want a short list of free tune-ups to try before spending money, this is a handy overview: https://www.tomsguide.com/computing/apple-desktops/5-free-ways-to-speed-up-your-slow-mac

Add more RAM if your computer keeps running out of breath

RAM is your computer’s short-term memory. When it runs low, the system starts swapping to storage. Even with an SSD, swapping can cause stutter.

Signs you need more RAM:

• The system pauses when switching apps
• Browsers crawl with a few tabs open
• Video calls glitch when you share your screen
• You see high memory pressure on Mac, or memory almost maxed on Windows

Simple targets for most people:

• 8GB: minimum for light use (email, web, docs)
• 16GB: better for heavy browsing, work apps, light photo or video edits

Check compatibility before buying RAM. Some laptops have soldered memory and can’t be upgraded.

Conclusion

A slow computer rarely needs one dramatic fix. It usually needs a calm sequence: restart, check storage and task load, free up space, trim startup apps, scan for malware, update, cool it down, then consider an SSD or more RAM.

Do one section at a time, and test the speed after each change. You’ll learn what actually helped, and you’ll avoid accidental mess.

Pick one action you can finish in 10 minutes today (empty Downloads, disable two startup apps, or run a full scan). Then keep a monthly clean-up habit, so your computer stays quick instead of sliding back into the mud.