How To

How to Fix Slow-Running Macs

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Is your Mac running slow? There can be several reasons why a Mac isn’t performing as it should, but they are often due to one or more of the following:

  • The Mac is old or its hardware can’t keep up. At some point the processor, drive, amount of RAM and/or graphics card simply can’t keep up with the latest software. New versions of macOS are generally compatible with Macs going back several years, but if yours is among the oldest supported by the current operating system, it may not have what it takes to be fully efficient.
  • There is a hardware problem. One of the components in your Mac has failed or is failing.
  • There is a software problem. The operating system or specific applications are not working as they should.

When troubleshooting a Mac, you go through a process of elimination. And troubleshooting can take a long time: you try a solution and then test to see if it works, sometimes waiting hours or even days to be certain. This is the only way to see if a solution is just a temporary fix or a permanent one.

When your Mac is getting slow, follow these troubleshooting steps to find what’s wrong and hopefully make it faster.

1. Back up your data

Whether the cause of your Mac’s performance issues are hardware or software, the first thing to do is ensure that you don’t lose any data. If there are hardware issues, then your Mac could potentially stop working, or your drive could be corrupted. You can use Apple’s Time Machine and Intego Personal Backup to back up your Mac. Ideally, you should use both: if you have multiple backups, and your Mac fails, this is the best way to ensure that you don’t use data: sometimes backups get corrupted, or their drives fail too. [This article]( tells you all about backing up your Mac.

2. Restart your Mac

Restarting your Mac is quick and easy, or at least it should be. When you restart your Mac, it clears the memory and forces any processes that may have been stuck to reload. The amount of time it takes for your Mac to go from black screen to loading your desktop can also be a good indication of where to look for issues. Most Macs, regardless of configuration and operating system version, should be up and running in no more than one minute or two; Macs with SSDs should go to the login screen in seconds. If the startup process takes longer, this doesn’t give clues as to what’s wrong, but it does suggest that something is happening when the Mac loads macOS rather than later.

If the restart process takes a long time, try again after disconnecting any peripherals connected to the computer, especially hard drives. Sometimes problems with external hard drives can slow down Macs, as the Mac is trying to read and perhaps index the drive for Spotlight searches. And at other times, even keyboards or mice can have issues that conflict with your Mac.

3. Check Resource Usage

If a restart did not solve your issues, or only fixed them for a short time, you should check how your Mac’s hardware is being used. Is your Mac using too much RAM and running out of memory? Are certain stuck processes causing your Mac to slow down? macOS has a useful utility called [Activity Monitor]( This utility gives you a live view of your Mac’s processor, RAM, energy, disk, and network usage. You can find this utility in Applications > Utilities.

First, set up Activity Monitor to make it easy to use:

  1. From the View menu, select Update Frequency, and then set it to its lowest value, 5 seconds. This makes it easier to see what’s happening; the display won’t change too quickly.
  2. In the same menu, make sure you check All Processes. Processes are apps that you see, and those that run in the background; your Mac runs dozens of different processes.

Activity Monitor shows all processes in real-time. The information is sorted into different tabs that display processes in the category specified, and each one can help you narrow down the issues you’re having.

The following is an overview of the various tabs in Activity Monitor, as well what to look for in each category:


Is a certain app or process causing excessive CPU load on your Mac? If a process is consistently taking up a high percentage of processor power, it may prevent other apps, or macOS itself, from doing all that it needs. You can quit that process to see if it resolves the performance issues. To do this, either quit the app, if it’s something you launched manually, or, if not, click it in Activity Monitor to select it, then click the X button in the toolbar. Click Quit. If that doesn’t work, try again, clicking Force Quit.

Read about other methods for force quitting apps on macOS.

If you don’t know what the process belongs to – it could be part of macOS, or part of a third-party app – do a search online to see what it is and how to address any issues with it. If the process clearly states what it is, you know which application might be the cause of the issue. You also want to check the graph and information at the bottom of the window.

No matter how many cores your Mac’s CPU has, these stats show how 100% of your processor power is used. It’s not uncommon for certain apps to use the CPU to its maximum at times – for example, when you’re rendering video – but this shouldn’t happen often. Also, when the CPU usage is consistently high, you’ll hear your fans running.

If the Idle number is very low, or near 0% consistently, then your processor simply doesn’t have the juice to take on any new tasks and is probably struggling with the tasks that are already running. Try running fewer applications simultaneously to see if that takes some load off the processor.


Equally as important as CPU load, if not more important, is the memory (RAM) in your Mac. macOS itself and every application that runs on it require RAM to function, and if it runs out of available RAM, the operating system starts to use your startup drive as temporary RAM to avoid crashing. Your Mac’s drive – even if it’s an SSD – is much slower than RAM chips, so this will have a huge impact on overall system performance.

Memory management has improved a great deal in recent years, however, and you’re unlikely to run out of RAM on a recent Mac. In addition, Apple’s new Macs running Apple silicon manage memory even more efficiently.

But sometimes apps have “memory leaks,” where they keep using memory even if they don’t need it. Check the Memory pane and see if you have such an app; below, there’s an app using more than 111 GB on my iMac, which only has 16 GB RAM. You’ll need to quit or force quit apps like this, and try reinstalling them, or contacting the developer to see if there’s a fix.

Also, if you’re running too many apps, then your Mac will have to write a lot of virtual memory to disk. At the bottom of the Activity Monitory window, look at Swap Used: if this number is high, quit the apps using the most RAM, if you don’t need them.

If your Mac really doesn’t have enough RAM, you may need to limit your app usage: instead of leaving, for example, your email app open all the time, quit it when you’re not checking or working with email. And check the RAM used by your web browsers: these apps are notorious for using a lot of RAM. Quit them often to free up RAM.


If you use a laptop, this tab can help you identify which applications are using the most energy, and reducing the amount of time you can use your Mac each day.

The Energy Impact column shows the current power usage, but this varies a great deal depending in which apps you use. The most important column is 12 hr Power. This shows which apps have used the most power over the past twelve hours, including time when your Mac was asleep. If your laptop’s battery life is insufficient, check here to see if you’re using an app that’s depleting the battery.


The Disk category shows the amount of data that is read and written for your entire system (all drives). If there’s an app that is reading or writing a lot of data, it could slow down your Mac and cause other tasks to run slow. Though remember that if you have automatic backups running, it’s normal to see a lot of data on this pane. If you use Time Machine, you’ll see the backupd process at the top of the list, and if you use other backup software, such as Intego Personal Backup, it should show up there as well.


While a slow network won’t really slow down your Mac, it will make any activities you perform that require data to be uploaded or download slower. The Network tab shows you how much data is sent and received, and you can find out if any apps are sending or receiving a lot of data over your local network, or over the internet. This could slow down your Mac because the apps reading or writing from your drive.

Of course, the issue may be your Internet connection itself; in this case, use an online speed test, such as [](, to see if you’re getting the bandwidth that you’re paying for.

4. Check available storage space

One common cause for Mac slowdowns is when your startup drive gets full. You need disk space to store files, but also to use virtual memory. If you run out of space on your drive, then any task where virtual memory is needed may be slow.

To check your Mac’s available storage, go to the Apple Menu > About This Mac > Storage. You’ll see something like this:

If you’re running out of space on your drive, you’ll need to move some files. You can use Optimized Storage, which we explain in [this article](, and have a look at Intego’s Mac Washing Machine, which can help you delete unneeded files, such as caches.

If you frequently run low on drive space, then you’ll need to move files to an external drive, and consider upgrading the drive in your Mac, if possible, or getting a larger drive on your next Mac.

5. Test the Hardware

Is your Mac just spinning when you ask it to do something? Your software may not be the cause of lagging issues. A failing drive, faulty RAM, or other hardware issues can sometimes cause the same type of symptoms. For example, the dreaded spinning beachball could be caused by a software or hardware problem.

Using the above steps, if the issue is caused by software, you should have a pretty good idea of what the culprit is; however, to test your hardware some different tools are required. There are tools built into your Mac you can to use to help identify hardware issues that may cause a slow Mac.

You can use these tools to test your Mac’s hardware:

Disk Utility

Disk Utility is an app that you can use to erase, format, and partition drives, and you can also use it to check if your drives are running smoothly. You can find it in Applications > Utilities.

Select your drive and click the First Aid button. This is a good first check, and you can run it on your startup drive, or external drives, to check their integrity. Disk Utility will tell you if your disks are running correctly, will repair some issues, and will tell you if there are more serious problems that it can’t fix.


Since macOS Catalina, using Disk Utility’s First Aid function has gotten a bit more complex than it was in the past. Choose View > Show All Devices, and you’ll see that a startup drive contains multiple items.

There are volumes, containers, and disks, and the part of your drive that contain the macOS system software mounts as a *snapshot*. When you run Disk Utility’s First Aid feature, you should run it on volumes, then containers, then disks. [This Apple support document]( gives you more information on using First Aid.

Apple Diagnostics

Your Mac has basic hardware test software built-in. To access it, restart your Mac and hold down the D key immediately, if the Mac has an Intel processor. If your Mac has an Apple processor, press and hold the power button until you see the startup options window, then press Command-D. More instructions about using Apple Diagnostics can be found here.

Apple Diagnostics will be able to tell you if there are problems with certain parts of your Mac. [The various codes it displays](, in case of problems, will indicate what is wrong, and what you should do next.

For example, if there’s a problem with the fan on your Mac, this could prevent the computer from using its processor to its maximum potential, slowing down your Mac. Or there could be a problem with the RAM, limiting its efficiency. Apple Diagnostics can check these potential issues, and more.

6. Take Your Mac to Apple’s Genius Bar

When you have checked the software and the hardware but can’t find anything wrong, you can always get more help. If you have Apple Care support for your Mac, call Apple, and they’ll help you. If not, take the Mac to Apple’s Genius Bar. They will do their own checks of the hardware and the operating system, and they will let you know what needs to be done. If you don’t have a local Apple Store, then you can find an Apple authorized service provider. Contact [Apple support]( to find one near you.


How can I learn more?

Each week on the Intego Mac Podcast, Intego’s Mac security experts discuss the latest Apple news, security and privacy stories, and offer practical advice on getting the most out of your Apple devices. Be sure to follow the podcast to make sure you don’t miss any episodes.

You can also subscribe to our e-mail newsletter and keep an eye here on Mac Security Blog for the latest Apple security and privacy news. And don’t forget to follow Intego on your favorite social media channels: Facebook, Instagram, Twitter, and YouTube.

About Jay Vrijenhoek

Jay Vrijenhoek is an IT consultant with a passion for Mac security research. View all posts by Jay Vrijenhoek →