Over time, an iMac (or any Mac computer) can slow down for a number of reasons.
Cluttered hard drive, loaded login items and launch agents, too many apps running in the background, even macOS itself (for example, the latest Catalina 10.15) could be the possible causes.
The slow performance of iMac can also be caused by inadequate hardware, for example, internal hard drive is aging and underperforming, not enough RAM (random access memory) to handle large application requests, etc.
When an iMac slows down, our productivity at work tends to decrease due to the emotional consequences. Scientific study shows frustration caused by slow computer affects our health, shocking right?
That’s why we wrote this article – by sharing a list of handy tips that help speed up an iMac and implementing some of them, you can make your iMac fast again.
1. Optimize iMac startup
If your iMac takes more than 30 seconds to fully boot up and reach the desktop screen, chances are you have too many login items or you are launching agents (app services that automatically run back – plan). In other words, there may be too many third-party apps or services opening once you press the start button on the back of your iMac. When the list of login items adds up, it’s no surprise that your iMac is slowing down.
Fortunately, disabling unnecessary login items is an easy task. Just click on the Apple logo at the top left of the main screen, click System Preferences> Users & Groups> Login Items. Here you can select the items you don’t want and click the minus “-” sign to turn them off.
On the flip side, those sneaky “launch agents” may also have been added to your startup. Unfortunately, it is not easy to turn them off via the above technique as they are often not displayed in the login item list. But you can use an app like CleanMyMac to locate and delete them easily.
Simply download CleanMyMac to your iMac, install and open the app. Under “Extensions” find the function “Launch Agents” and here you can disable or enable any applications or support services. By the way, you can also manage login items there.
2. Close the applications running in the background
For some apps, even if you clicked the red “x” sign in the upper left corner, they may still be running in the background. If you have too many processes running at once your iMac’s speed can be drastically affected, even worse the whole Mac freezes to death. And you will have to force quit apps or reboot hard.
To see which apps and services are consuming a lot of system resources (CPU, memory, battery, etc.), use the Activity monitor app (or IStat menus) to find out. Apple has a support article on how to properly use this utility. Watch this video to learn more:
3. Clean the iMac hard drive
All Macs will run slowly once the startup disk is nearly full. Some macOS features or utilities may not even work well with low storage. In addition, lack of free space is often a cause of more frequent freezes, freezes and crashes.
To move more space on your iMac hard drive, your first step is to get the storage overview. To do this, click on the Apple icon, then About this Mac. Under the Storage room section, you can see how much space is available on the current disk. Different colored blocks indicate different types of files, such as movies, photos, or apps.
Then clean up junk files like system junks, unused apps, large old items, etc. CleanMyMac is a time saver, it helps you determine which specific files take up the most space and indicate which ones can be deleted or transferred safely.
Meanwhile, you can also use Gemini 2 to quickly get rid of such duplicate and similar files (especially photos). CleanMyMac and Gemini are both designed and developed by the same company.
4. Run the correct version of macOS
Depending on the model of iMac you are using, you might want to check if the macOS version your iMac is running is the best option. For example, the latest macOS Catalina doesn’t always guarantee better performance, especially it requires at least 4GB of memory and 12.5GB of available storage space, or up to 18.5GB of storage space. when upgrading from OS X Yosemite or earlier.
If your iMac’s hardware configuration is a bit behind, chances are it will run slowly after updating. In fact, many iMac users have reported the issue.
So know your iMac and run the correct macOS. To check the macOS version of your iMac, click on the Apple logo> About This Mac, there you will see the information. Then you can choose to upgrade to a newer macOS or downgrade to a macOS.
5. Remove unwanted apps and extensions
How many times have you downloaded an app or browser plugin but only used it once and later completely forgot about its existence?
Days and months later, you might surprisingly find that your iMac is filled with such unnecessary apps / extensions. Most of them won’t do any harm except by taking a little storage, some may run silently when you start your Mac or when you surf the internet through Safari, Chrome, Firefox, etc.
So it’s always a good idea to remove those unnecessary apps and plugins to give your iMac a little boost in performance.
The easiest way to get started is to go to the Applications folder, drag and drop those unwanted apps to the Trash, and empty the Trash.
To clean up browser plugins / extensions, open your browser settings and you should be able to find the right place to manage these extensions. For example, I am using Chrome (ver. 64 for Mac), just click on the three dot icon, then click on More Tools and find Extensions. There I can see all the installed plugins and choose to remove or disable the unwanted ones.
6. Add more RAM
RAM (random access memory) plays an important role in handling application requests. If you’re a designer or developer who uses an older iMac for video or photo editing projects, chances are RAM is the bottleneck. When the RAM is depleted, your iMac will have to fail over to use the virtual memory on the disk, which will eventually slow down the performance of the iMac.
The solution? Consider adding extra memory! If you decide to do so, be sure to check how many GBs your iMac can add from this Apple resources page. For example, for most 27-inch models, the base memory is 8 GB and you can add up to 32 GB.
For RAM upgrade options, consider 16GB Crucial Kit (8GB x 2) and 32 GB OWC for the 27-inch iMac 2017 with Retina 5K display.
Also, don’t forget to watch this video before opening your iMac mainframe to install additional RAM.
7. Replace your iMac hard drive with an SSD
For older iMacs, replacing the current hard drive or fusion drive with an SSD (solid state drive) can significantly improve the speed and performance of your Mac. As with adding more RAM, be sure to check which SSDs are compatible with your model of iMac.
For iMac SSD options, consider this set of OWC SSD upgrade if you are using a 2012-2015 iMac or OWC Mercury Electra you are on a 2011 model iMac.
This video shows everything you need during the replacement process.
That’s all we wanted to share with you. Hope you find this iMac performance troubleshooting guide useful. Let us know which way (s) you find most useful to speed up your iMac? We are here to hear from you.