Slow Mac: what to check yourself, and when a reinstall helps

A Mac that has become slow is rarely broken. Most often it is software that has piled up over the years. Here is what to check yourself first, and when it makes sense to start over with macOS.

Five things you can check yourself

1. Is the disk nearly full? Go to System Settings, General, Storage. macOS uses free space as working space, and with less than 10 to 15 percent free, everything slows down. Large videos, old phone backups and downloads are the usual culprits.
2. What is using the power? Open Activity Monitor and sort by CPU, then by memory. A single app that has hung can make the whole machine sluggish.
3. What starts automatically? Under System Settings, General, Login Items, you will find the apps that start when you log in. Remove the ones you do not use.
4. Is macOS up to date? Updates often fix exactly the kind of bug that slows a machine down.
5. When did you last restart? Many people just close the lid for months. A restart clears out the memory.

When a reinstall helps

If none of that helps and the machine is otherwise fine, a fresh install of macOS is often the most effective fix. It helps especially when:

• the machine is slow from startup, before you have even opened anything.
• apps quit for no reason, or updates fail.
• it has been through years of updates, migrations from old machines and apps you have long forgotten about.

A reinstall from macOS Recovery puts a clean operating system on without deleting your files. But always make a Time Machine backup first. The one time it goes wrong is the only time that counts.

When it does not help

We would rather say it now than afterwards: a reinstall does not make a machine faster than it was from the factory. If your MacBook is from 2016 with 8 GB of memory and you work in heavy apps or with lots of tabs open, software is not the problem. The machine has become too small for what you use it for.

If it shuts down suddenly or is only slow on battery, look at the battery first. Read our guide on battery condition on a Mac.

Want us to do it?

A macOS reinstall costs the same whatever the model, because it is labour and not a part. You see the price in our price calculator. We come to you, and you get the machine back ready to log in.

If the machine is being sold or given away, we also do a full wipe and reset, so nothing of yours goes with it.