How to Speed Up a Slow Windows 11 PC (and Keep It Fast)

Your PC was fine a year ago. Now it takes forever to boot, everything feels sluggish, and you're wondering if it's time for a new one. Before you spend any money, try these fixes. Most of them are free and take a few minutes each.

I've been fixing PCs in St Helens since 2008, and nine times out of ten, a "slow computer" doesn't need replacing. It hasn't been dropped or hit by lightning. It's just been left to fill up with junk and dust for a few years. The first half of this post gets it fast again. The second half is the handful of habits that stop you ending up back here.

1. Disable Startup Programs

This is the single most common cause of a slow PC. Every program you install tries to add itself to your startup list, and after a year or two it's not unusual to find 15 or 20 of them loading at boot, fighting for resources before you've even opened anything.

Press Ctrl+Shift+Esc to open Task Manager, then click the Startup apps tab. Anything you don't need running the moment you log in can go. Right-click it and choose Disable.

Common culprits that don't need to be there:

• Spotify, Discord, Steam and Teams, unless you genuinely open them every single time you switch on
• Adobe Creative Cloud, which opens when you launch an Adobe app anyway
• Updaters like Adobe Updater and Java Update Scheduler
• Manufacturer "helper" apps. HP, Dell and Lenovo all love adding these and they do nothing useful
• Printer software. HP especially installs a whole suite. You don't need it, Windows handles printing fine on its own

2. Uninstall Software You Don't Use

Go to Settings → Apps → Installed apps and sort by size. Then sort by install date, which is handy for spotting things you don't remember putting there. You'll probably find trials that expired years ago and pre-installed bloat from the manufacturer.

Uninstall anything you don't use. If you're not sure what something is, leave it. Old printer software, browser toolbars, free antivirus trials and "PC cleaner" tools can safely go.

3. Turn Off Visual Effects

Windows 11 has animations, transparency, shadows and smooth scrolling everywhere. It looks nice, but on older hardware it's burning resources on eye candy instead of running your apps.

Open the Start menu and search for "performance", then click Adjust the appearance and performance of Windows. You'll see this dialog:

Select "Adjust for best performance" to turn everything off, then tick "Smooth edges of screen fonts" back on. Without that, text looks awful. Click OK and the difference is immediate, especially on older machines.

4. Check for Malware

Some malware is designed to be invisible while it chews through your CPU. Crypto miners are a common one. Your PC feels slow but you can't see why.

Open Windows Security (search for it in the Start menu), go to Virus & threat protection, and run a Full scan, not just a Quick scan. It checks every file on the system and takes a while. Leave it running over lunch.

5. Free Up Disk Space

A nearly full drive doesn't just stop you saving files. It actively slows the PC down, because Windows needs free space for virtual memory, temp files and updates. Once your C: drive goes past about 85-90% full, things get sluggish and unstable.

Go to Settings → System → Storage to see what's using the space. The usual suspects:

• The Downloads folder, stuffed with installers and files you opened once
• The Recycle Bin, quietly holding months of deleted files. Right-click it on the desktop and empty it
• Games. A single modern game can be 50-100GB. If you've stopped playing it, uninstall it, you can always download it again
• Teams and Slack, which build up gigabytes of cached data without telling you

Click Temporary files on the same Storage page and clear what you're comfortable removing. But the real gains come from the old Disk Cleanup tool.

6. Run Disk Cleanup as Administrator

This is the step most people miss. The normal Disk Cleanup tool only shows your user files. Running it as administrator unlocks system-level cleanup (old Windows updates, previous installations, delivery optimisation files). This can reclaim gigabytes.

1. Open the Start menu and search for Disk Cleanup
2. Select your C: drive and click OK
3. When it opens, click "Clean up system files"
4. Select your C: drive again and wait for it to scan
5. Tick the big items (see below)

That "Previous Windows installation(s)" entry is the Windows.old folder, left behind after major Windows updates. It can easily be 20GB+ and does nothing once you're happy the update went in fine.

7. Turn Off System Restore

This one surprises people, but System Restore can genuinely slow your PC down. It hooks into file system operations to track every change, creating restore points in the background. On a machine that's already struggling, that overhead adds up, and the restore points themselves eat disk space, which makes the problem worse.

System Restore is a leftover from the XP and Windows 7 era when it was your only real recovery option. Windows 11 has much better ones built in:

• Reset this PC, which reinstalls Windows while keeping your files
• The Windows Recovery Environment (startup repair, rolling back updates, command prompt access)
• An in-place upgrade repair, which reinstalls Windows over the top without losing anything
• Driver rollback in Device Manager, if a driver update causes problems

To turn it off, search for "Create a restore point" in the Start menu, select your C: drive, and click Configure:

Select "Disable system protection" and click OK. Then click Delete to remove existing restore points and reclaim the space. You won't miss it. Your real safety net is a proper backup of your files, not restore points.

8. Get Windows Updates Sorted

Updates are annoying. They pop up at bad moments, take ages, and once in a while they break something. But a pending update that's been trying to install in the background for weeks can drag the whole machine down. Go to Settings → Windows Update, let it finish whatever it's doing, and restart when it asks.

While you're there, check which version you're on. Windows 11 24H2 stopped getting security updates on 13 October 2026, so if that's what yours says, it's time to move up. I covered what's in the 26H2 update and how to get it.

Occasionally a bad update is the cause. If your PC got noticeably slower right after one, go to Windows Update → Update history → Uninstall updates and remove the most recent one to see if that helps.

9. Clear Out the Dust

Dust doesn't get blamed for slowness nearly as often as it should. It packs into heatsink fins and clogs fan blades, so the CPU runs hotter, the fans get louder, and the processor throttles itself to avoid damage. A PC that's quick for the first ten minutes and then turns to treacle is often just cooking itself.

On a desktop, take the side panel off and use a can of compressed air on the CPU heatsink, the case fans and any dust filters. Hold each fan still with a finger while you blast it. Letting it free-spin from compressed air can damage the bearing.

Laptops are fiddlier. It usually means taking the bottom panel off (most are held on with small Phillips screws) and blowing out the fan and heatsink fins. If you're not comfortable opening it up, get someone to do it for you.

10. Upgrade Your Hardware

If you've tried everything above and it's still slow, the bottleneck is probably hardware. Two upgrades make the biggest difference:

Replace the hard drive with an SSD

This is the single biggest upgrade you can make to any PC. If your computer takes more than 30 seconds to get to the desktop, it almost certainly has a traditional spinning hard drive. Swapping it for an SSD (solid state drive) makes everything dramatically faster: boot time, opening programs, file transfers, everything.

An SSD upgrade is a simple swap, and your data can be migrated across so you don't lose anything. It's the upgrade I recommend most often because the difference is night and day.

Add more RAM

If your PC grinds to a halt when you've got a few browser tabs open and a couple of programs running, you might not have enough RAM. Open Task Manager (Ctrl+Shift+Esc), click the Performance tab, and check Memory. If it's consistently above 80-90%, more RAM would help.

8GB used to be plenty, but with modern Windows and the way browsers eat memory, 16GB is the sweet spot for most people now.

Keeping It Fast Once It's Sorted

Here's the annoying truth. Do all of the above, change nothing about how you use the PC, and in eighteen months you'll be reading this post again. None of the upkeep is complicated. It's just easy to forget, so here it is as a checklist:

Stop Installing Junk

Half the slow PCs I see in St Helens are slow because of software that should never have been installed. Free programs that came bundled with toolbars. Browser extensions from dodgy websites. "Driver updater" tools that are close to being scams.

Download from the developer's own website or the Microsoft Store, never a random download site. Read each installer screen properly, because a lot of free programs try to slip extra software in during setup, and untick anything you didn't ask for.

Skip "PC cleaner" and "registry fixer" software altogether. CCleaner, Advanced SystemCare and the rest of that crowd had a purpose years ago. On modern Windows they cause more problems than they solve, and the built-in tools above do the job safely. Same goes for paid antivirus on most home PCs: Windows Defender is enough, and I explained why in my post on whether you actually need antivirus.

When It's Actually Time for a New PC

Sometimes the honest answer is that the machine has had its day. If it's 8+ years old, has a low-end processor, and you've already maxed out the RAM and put an SSD in, there's only so much you can do. But that's genuinely rare. If you're stuck deciding, I've written about whether to repair or replace a PC.

If you'd rather hand it over and have someone work through all of this for you, I do computer repair and tune-ups in St Helens, including the cleanup, dust-out and updates in one go, and can usually have it back to you within a day.

Mark

Mark has been fixing computers since the late '90s and went self-employed in 2008. Based in St Helens since 2013, he works evenings and weekends from his home in Laffak, doing friendly, affordable repairs for PCs, laptops, and Macs. See reviews on Google