So your machine used to boot in 20 seconds, and now you’ve got time to make a coffee, drink it, and reconsider your life choices before the desktop even shows up ? Yeah, I’ve been there. The frustrating part is that a slow computer is rarely caused by one big thing. It’s usually a pile-up of small issues, and most of them you can fix yourself without nuking Windows or paying someone to “reinstall everything.”

Before we get into the list, let me be honest with you : not every slowdown has a software fix. Sometimes the hardware is just done, sometimes a component is dying quietly, and sometimes you genuinely need a second pair of eyes. If after going through these steps your PC still acts like it’s running underwater, you can get a remote diagnosis from a technician here : https://depannage-informatique-en-ligne.com. Honestly, it’s often quicker than spending a Saturday troubleshooting alone. But before that, let’s check the obvious stuff. Most of the time, you’ll find the culprit in this list.

1. Too many programs launching at startup

This one is THE classic. You install Spotify, Discord, Steam, Adobe something, OneDrive, your printer drivers… and every single one of them decides it deserves to launch when Windows boots. Result ? Your PC spends its first five minutes choking on background processes before you even open a browser.

The fix : Right-click the taskbar, open Task Manager, go to the “Startup apps” tab, and disable everything you don’t actively need at boot. Be brutal. Spotify doesn’t need to start with Windows. Neither does Teams, unless your job depends on it.

2. Your hard drive is still a mechanical HDD

If your computer is more than 6-7 years old and you’ve never replaced the disk, there’s a very good chance you’re still running on a spinning hard drive. And honestly ? In 2026, that’s the single biggest bottleneck you can have. An SSD is roughly 5 to 10 times faster for everyday tasks.

I’ve seen people swap an HDD for a basic SATA SSD on a 10-year-old laptop and suddenly the thing feels new. Genuinely. If you can spend around 40 to 60 euros on a 500 GB SSD, do it. It’s the best upgrade-to-price ratio in computing right now.

3. Not enough RAM (and Chrome eating it all)

Got 4 GB of RAM? In 2026, that’s basically nothing. Chrome alone can eat 2 GB before you’ve even opened a real tab. Windows 11 wants 8 GB minimum to feel comfortable, and 16 GB if you want to multitask without wanting to throw your laptop out the window.

Open Task Manager, check the “Memory” line. If you’re constantly above 80%, that’s your answer. Adding RAM on a desktop is easy and cheap. On a laptop, it depends on the model – some are soldered, some aren’t.

4. Disk almost full

Did you know Windows needs free space to breathe ? When your C: drive is over 90% full, everything slows down – temp files can’t be created properly, virtual memory gets cramped, updates fail. Keep at least 15-20% of your disk free.

Quick wins : empty the Recycle Bin (yes really), run “Storage Sense” in Windows settings, uninstall games you haven’t touched in two years, and clear your Downloads folder. You’ll be amazed how much junk lives there.

5. Malware, adware, or that “free PDF converter” you installed in 2022

Sometimes the slowdown isn’t your fault per se – it’s something running in the background that shouldn’t be there. Crypto miners, browser hijackers, sketchy toolbars… they all eat CPU silently.

Run a full scan with Windows Defender (it’s actually decent now), then a second opinion with Malwarebytes Free. If both come up clean, malware probably isn’t your problem. If they find stuff, well… you’ve got your culprit.

6. Outdated drivers, especially graphics

Old drivers can cause weird stutters, especially on the GPU side. If you’ve got an Nvidia or AMD card, go to their official site (not some random “driver updater” tool, please) and grab the latest version. For laptops, the manufacturer’s support page is your friend – Dell, HP, Lenovo, all have driver download pages tied to your serial number.

7. Windows updates pending in the background

Have you been postponing updates for three months ? Windows is probably trying to download and install them every time you turn the PC on, which absolutely kills performance. Just let it finish. Plug the laptop in, go make dinner, come back. Sometimes the fix is just letting the machine do what it’s been begging to do.

8. Overheating and dust

This one is sneaky. When a laptop overheats, the CPU automatically slows itself down to avoid damage – it’s called thermal throttling. You feel it as random slowdowns, especially under load. The fan goes wild, the bottom of the laptop becomes a frying pan, and everything lags.

Open it up (or get someone to do it), blow out the dust, repaste the CPU if you’re comfortable. On a desktop, just cleaning the fans with compressed air can drop temperatures by 10-15°C. Massive difference.

9. Browser overload

Be honest. How many tabs do you have open right now ? 30? 50? Each tab in Chrome or Edge is essentially a small program running in memory. And those extensions you installed and forgot about ? Yeah, they’re running too.

Close tabs you don’t need (use bookmarks, that’s literally what they’re for), audit your extensions, and consider switching to a lighter browser like Firefox or Brave if Chrome feels heavy on your machine.

10. Background apps and Windows services you don’t need

Windows runs dozens of services in the background, plus apps like OneDrive syncing constantly, Xbox Game Bar, Cortana, the Search Indexer rebuilding itself for the 50th time… most of them are useful for someone, but maybe not for you.

Type “Services” in the Start menu, but be careful here – disabling the wrong service can break things. If you’re not sure what something does, leave it alone or look it up first. Same with the “msconfig” tool. Power, but with footguns.

So… what should you actually do first ?

If I had to give you a quick action plan, it’d be this : clean up startup apps, run a malware scan, check disk space, and look at how much RAM you’re using under normal load. Those four checks take maybe 20 minutes and solve probably 70% of slowdowns.

The other 30%? That’s where it gets specific to your machine, your usage, and sometimes hardware that’s genuinely on its way out. And at that point, no amount of YouTube tutorials replaces someone actually looking at your config and telling you “your SSD has 12% health left, replace it before it dies.”

What about you, what’s the symptom that’s bothering you the most right now – slow boot, frozen browser, fan going crazy ? Because the answer kind of depends on that. Start with the most annoying one, work your way down, and don’t reinstall Windows unless you’ve genuinely tried everything else. Reinstalling is the nuclear option, and honestly, it’s overrated.