Macs have a reputation for being fast and stable, but they can slow down over the years too. In older models, the most common cause is the same as on a PC: a mechanical hard drive. But there are macOS-specific causes as well, which we cover here.
Most common causes of a slow Mac
1. A mechanical hard drive (on Macs before 2015)
iMacs and MacBook Pros from before 2015 often shipped with mechanical hard drives. Switching to an SSD is the biggest single upgrade: a 2012 iMac with an SSD outperforms a newer one still running an HDD for everyday use.
2. Not enough RAM
macOS runs smoothly on 8 GB of RAM, but with 4 GB and lots of Safari or Chrome tabs open, the system starts using disk space as virtual memory (swap), which slows things down dramatically.
3. Storage almost full
macOS needs free space to run properly — ideally at least 15-20% free. Check under "Apple menu → About This Mac → Storage".
4. Login items
Go to "System Settings → General → Login Items" and remove any programs you don't need starting automatically.
5. Outdated macOS
The newest macOS versions are usually optimised for newer models and can sometimes slow down older ones. If your Mac got slower after a macOS update, that version may not suit your hardware well.
6. Spotlight re-indexing
After an update, Spotlight may be re-indexing all your files. If the fan is loud after an update, give it a few hours to finish.
What to do if your Mac is still slow
We have plenty of experience with Macs. We diagnose the problem, clean up the system and, if needed, carry out an SSD upgrade on iMac or MacBook. The result is a Mac that feels new again, for a fraction of the cost of replacing it.