Quick wins
- Restart it properly (not just closing the lid)
- Install pending Windows or macOS updates
- Close browser tabs you aren't using
- Uninstall programs you don't recognise or use
Check your storage
Computers slow down badly when the drive is nearly full. Aim to keep at least 15% free: move photos to the cloud or an external drive and empty the recycle bin.
When it's hardware
If your laptop still has a spinning hard drive, swapping it for an SSD is the single biggest speed boost, often making a 5-year-old laptop feel new. More RAM helps too.
Beware 'PC cleaner' ads. Many are scareware.