My laptop is slow: 5 real causes and how to tell which one is yours
Kevin Muñoz · 6 May 2026 · 7 min read
Every week someone comes in convinced they need a new computer. Most of the time they don't: the machine has just one thing wrong, and fixing it costs a fraction of a new one. Before you spend 700 €, take ten minutes to find out what's wrong.
First: check Task Manager
Press Ctrl + Shift + Esc and go to the Performance tab. With the computer on and doing nothing in particular, look at which bar is stuck at the top. That's your culprit, and each one points to a different repair.
1. The mechanical hard drive: the number one cause
If your laptop is more than five years old, chances are it has a spinning-platter drive. That drive was slow the day it left the factory, and today Windows demands three times as much from it. The classic symptoms: it takes two minutes to start, the mouse moves but nothing responds, and you hear a whirring when opening folders.
Replacing it with an SSD is by far the upgrade you'll notice most. I go into detail in “Fitting an SSD to an old computer”.
2. Too little RAM
With 4 GB, Windows 11 and a browser with ten tabs, you've already run out of memory. When that happens, the system starts using the disk as emergency memory and everything crawls. The symptom: it's fine at startup and gets worse as you open programs.
Going from 4 to 8 or 16 GB costs 25 € in labour plus the modules, and on many laptops it takes fifteen minutes. Two warnings: some slim models have soldered memory and can't be upgraded, and this year modules are at record prices because of the chip shortage, so parts make up a bigger share of the quote than ever.
3. Overheating
Dust clogs the heatsink and the thermal paste dries out. When the processor goes over 90 degrees it throttles itself to avoid burning, and your laptop performs like one at half the price. The symptom is unmistakable: the fan roars, the keyboard area gets hot and the computer gets slower the longer it's on.
An internal clean with fresh thermal paste brings it back to normal. It's maintenance, not repair: it's worth doing every two or three years.
4. Too many startup programs
Every program you install asks to start with Windows. Over the years you end up with fifteen things fighting for the CPU as soon as you switch on. In Task Manager, Startup tab, disable everything you don't use every day. It's free and you'll notice it.
Watch out for one special case: two antivirus programs installed at once get in each other's way and drag performance down. The one built into Windows is enough for normal use.
5. A full disk
Windows needs free space to work. With less than 10% of the disk free, everything starts going wrong, and below 5% the system becomes unusable. Check how much you have left in This PC: if the bar is red, that's your problem.
The “speed-up” programs and “registry cleaners” advertised online don't fix any of the above. At best they do nothing; at worst they install adware and make the problem they claimed to solve even worse.
Frequently asked questions
Does formatting fix it?
Only if the problem is software. If the disk is worn out or there isn't enough RAM, formatting gives you a few good days and then it's slow again. That's why it's worth diagnosing first.
Is it worth investing in an 8-year-old laptop?
If it only needs an SSD and RAM, almost always yes: for 100 € it gives you three or four more years of office use. If the battery, screen or hinge is also failing, then you need to do the maths.
How much do you charge to look at it?
Diagnosis is free. I tell you what's wrong and what it would cost before touching anything, and if it isn't worth fixing, I tell you anyway.
Shall we look at it before you buy a new one?
Free diagnosis in Matadepera and the surrounding area. If it can be fixed, I give you a fixed price; if not, I tell you without charging.