Has your iMac become slow? Does startup take minutes, does the spinning wheel keep appearing and do apps respond slowly? On an iMac with an Intel processor this is very often down to one part: the hard drive. On a newer iMac with an Apple chip the cause is usually elsewhere. This article explains how to find out why your iMac is slow, and whether an SSD, more memory or a new iMac is the best solution.
Blue Apple repairs iMacs and MacBooks in Amsterdam and fits SSDs in older iMacs.
Step 1: which iMac and which drive?
Choose About This Mac in the Apple menu and note the model and year. Click More Info or System Report and look under Storage (or SATA/NVMe): does it say hard drive, "Fusion Drive" or SSD? Many 21.5 inch iMacs up to 2019 had a 5400 rpm hard drive. That is very slow for today's macOS.
Step 2: what slows it down?
Open Activity Monitor and look at:
- Disk: is the drive constantly reading and writing, even when you do nothing? With a hard drive that is almost always the cause.
- Memory: is memory pressure yellow or red? Then you have too little memory for what you do.
- CPU: does one process keep using a lot? Quit it or remove the app.
See Activity Monitor explained.
Solution 1: an SSD instead of the hard drive
On an Intel iMac with a hard drive or Fusion Drive, an SSD is the biggest improvement you can get. Startup goes from minutes to seconds and apps open much faster. The screen has to come off, because the drive sits behind it. The screen is held by adhesive strips; after fitting the SSD new strips go on. Then we put macOS and your data back.
Solution 2: an external SSD as startup disk
If you do not want the iMac opened, you can install macOS on a fast external SSD and start from it. That works best over Thunderbolt or USB-C. Even over the older USB 3 ports it is much faster than a hard drive. Downside: there is always a drive attached to your iMac.
Solution 3: more memory
The 27 inch iMac has a small door at the back where you can add memory. On the 21.5 inch iMac the screen has to come off. More memory only helps if memory pressure is high. With a hard drive, an SSD usually helps far more than extra memory.
A slow 24 inch iMac with an Apple chip
On these iMacs memory and storage are fixed. If it is slow, check whether the storage is nearly full (leave at least ten percent free), which apps start at login and whether a macOS update is waiting. Also see Mac keeps freezing: causes.
Or a new one after all?
- If your iMac no longer gets macOS updates, it keeps working but becomes less secure over time. See updating an old Mac.
- If you do heavy work such as video or 3D, an iMac or Mac mini with an Apple chip is much faster than any Intel iMac.
- For mail, internet, photos and writing, an old iMac with an SSD is often fine for years.
Back up first
Make a Time Machine backup before any work. An old hard drive that gets slow may also be close to failing. See backing up.
What we do at Blue Apple in Amsterdam
We test the drive and memory, tell you the best solution for your iMac and what it costs, and restore your data after an SSD upgrade. Also read iMac repair in Amsterdam and see pickup and delivery if you cannot bring the iMac yourself.
Frequently asked questions
How much faster does an iMac get with an SSD?
With a 5400 rpm hard drive the difference is large: startup and opening apps become many times faster.
Do I lose my files with an SSD upgrade?
No, if there is a backup or the old drive is still readable, we put everything back.
Is a Fusion Drive not fast already?
A Fusion Drive combines a small SSD part with a hard drive. That beats a hard drive alone, but a full SSD is noticeably faster.
