Why Is My Computer So Slow? Common Causes and How to Fix Them
Computers rarely slow down for no reason. Open Task Manager (Ctrl + Shift + Esc) and look at what is busy: the processor, memory or disk. That one screen usually tells you where to start.
Too many programs at startup
Apps that launch with Windows quietly use memory and slow every boot. In Task Manager, open the Startup tab and disable anything you don't need the moment the computer starts.
The disk is always at 100%
If Task Manager shows the disk constantly maxed out, an old mechanical hard disk is the likely bottleneck. Moving to an SSD is often the single biggest speed improvement you can make to an older computer.
Not enough RAM
If memory is nearly full whenever you have a browser and a few apps open, the computer starts swapping to disk. For everyday office work, 8 GB is a sensible minimum and 16 GB is comfortable.
Malware and unwanted programs
Pop-ups, a changed browser homepage, unknown toolbars or a fan that runs at full speed while idle can mean malware. Run a full scan with your security software and uninstall programs you don't recognise.
A nearly full drive
Windows needs free space to work. Keep at least 15–20% of the system drive free by clearing downloads, emptying the Recycle Bin and moving large files elsewhere.
Overheating
Dust-blocked fans make the processor slow itself down to stay cool. If the computer gets hot and loud and then slows down, a cleaning and fresh thermal paste can bring back its performance.
When to get help
- Slowness continues after the basic clean-up
- The disk shows errors or makes clicking noises
- You suspect malware but can't remove it
- You want an SSD or RAM upgrade done with your data moved across
