slow mac

12 Reasons why your Mac or MacBook is so slow all of a sudden?

Without putting the Slow Mac or Macbook through an Apple Diagnostics test, it is impossible to say if you are experiencing one or more than one issue.

Your slow mac may have suddenly started or it may have become slower over time.

When programs become unresponsive and you see the spinning-wheel-of-death too often,

spinning wheel of death

… something is amiss and needs rectifying.

Only by running a full diagnostic can you accurately identify the problem.

If you live in , Western , the IT Guys WA can do this for you but we cannot do anything or quote prices until we have ‘Tested & Assessed' your device in our workshop.

You will need to bring or deliver your device to our workshop at :address: between :opening-hours:

No appointment is necessary.

A Test & Assess fee of :assess-fee: is required to be paid on drop-off and is non-refundable.

The following is a list of 12 potential problems we will test for plus some suggested fixes.

  1. HDD (Hard Disk Drive) or SSD (Solid-State-Drive) is full or nearly full.
  2. GPU (Video Card) Failing
  3. OS (Operating System) is out-of-date and in need of updating to a later version.
  4. Too many programs open for available RAM
  5. Virus or Malware needs removing
  6. Failed or Pending Mac OS (Operating System) update
  7. Hanging programs
  8. Battery is failing and needs replacing (MacBooks Only)
  9. Too many programs trying to open upon startup
  10. Too many items on your desktop.


1. Slow Mac? – HDD (Hard Disk Drive) or SSD (Solid-State-Drive) is full or nearly full.

macbook disk is almost full

When the HDD or SSD drive on your computer becomes full or almost full, the OS cannot use the disk space for “caching” and it causes programs to become slow and sometimes unresponsive.

If the HDD or SSD become critically low on storage you may see a warning, freeing up as much space as possible may improve performance if this is the only issue.

SSD Upgrade prices 2021
SSD Upgrade prices 2021
Macbook Air & Macbook Pro Retina SSD Upgrade prices
Macbook Air & Macbook Pro Retina SSD Upgrade prices

See also The Mac “Startup Disk Almost Full” Message and How to Fix It

2. Slow Mac? – HDD (Hard Disk Drive) or SSD (Solid-State-Drive) is old/failing and needs replacing

sick disk drive

If your Mac is slow to restart after a full power down or update and/or if you can hear an audible clicking sound and your computer is over four years old, the chances are that you have a failed or failing Hard Disk or SSD. Full diagnostics of the drive will be required by a service technician to determine if this is the case.

mac failed hdd

Apple Mac Repair Required?

If your computer is a pre-2012 model then it is most likely to have a conventional HDD, which is now > 5 years old and has a 50% chance of failing as well as slowing down due to age and an accumulation of old programs, utilities and old operating systems.

SSD Upgrade prices 2021
SSD Upgrade prices 2021

How old is my Mac?

You have two choices, replace the drive with another conventional HDD or upgrade to an SSD.

Upgrading or adding an SSD (Solid-State-Drive)

Solid State Drives (SSDs) have no working parts so you can read and write data to and from them very quickly. Think of them as a very large  Thumb drive or . They use the same technology.

SSD‘s range in size from 250 GB to 4000 GB (4 TB). Most commonly pre-installed HDD are 500 GB to 1 TB in size. Current prices for SSD's range from $220 installed.

SSD Upgrade prices 2021
SSD Upgrade prices 2021

old mac

See… How old is my Mac?

Simply replacing the old drive with a newer version of the same drive, will increase performance and data security but you are not going to get the same speed boost as upgrading to an SSD.

If your Mac is less than 5 years old but slower than usual, try a disk repair first.

See… How to run a disk repair on a Mac

3. Slow Mac? – HDD (Hard Disk Drive) or SSD (Solid-State-Drive) SATA Cable failing

failed sata cable

See… Macbook Slow? Could be the HDD or the SATA Cable?

4. Slow Mac? – GPU (Video Card) Failing

mac gpu

See… Mac video problems are bad news for iMacs and Macbooks and could signal it's end-of-life

5. Slow Mac? – OS (Operating System) is out-of-date and in need of updating to a later version.

mac os logo

Many problems are fixed by Apple releasing periodic OS (Operating System) updates.

Updating to the latest operating system will fix many issues and provide new features and compatibility with other devices. However, before making any updates :

a) Make a full Time Machine Backup of your computer

See… How to backup a Mac,

b) Make sure the new OS is compatible with your existing programs such as Adobe PS (if you use it) by reading the following guide.

See… Things you should check before updating the OS on a Mac

See… Are you Apple devices up-to-date?


6. Slow Mac? – Too many programs open for available RAM

mac memory

Earlier Mac's were shipped with 2GB RAM or less.

The later Mac OS such as Sierra and  and Mojave will only operate with a minimum 4GB of RAM. Latest MacOS needs 8GB RAM.

Adding extra RAM also increase the speed of certain memory hungry programs that do a lot of processing such as video and image editing and rendering programs including Auto CADiMovie and Final Cut Pro but generally will not be noticeable if you already have 8GB or 16GB of RAM

Extra RAM may help if you have multiple programs running at the same time, closing all but the essential ones may increase performance

Click on “Apple Symbol” > “Force Quit” and close any unnecessary programs and see if this resolves the issue.

force quit

7. Slow Mac? – Virus or Malware (Mackeeper) or (CleanMyMac) needs removing

Yes, Mac's do get viruses that can affect performance. The following article gives advice on setting up an program that does not affect performance adversely.

See… Apple Mac' do get viruses? This is not a joke.

A bigger problem for performance is the installation of unnecessary programs, cleaners and utilities which are commonly known as “bloatware

Some FREE “utility” programs actually slow performance even more than usual and  try and trick you into purchasing the “paid” version to solve the issue.

Be very wary of third-party programs that offer to “clean” or “speed-up” your computer.

See.. Mackeeper is Malware and need removing.

8. Slow Mac? – Failed or Pending Mac OS (Operating System) update


Performance issues have been noticed when there is an attempt to “upgrade” the OS that fails, leaving the computer in a state of “limbo” not being able to revert to the previous OS version and not being any to complete the upgrade to the current one.

The following article explains the problem and identifies the symptoms.

See… Upgrading to the latest OSx or MacOS

9. Slow Mac? – Hanging or un-responsive programs

After upgrading your operating system to Sierra, High Sierra or higher, you may well have a program already installed that is not designed to run on that OS or you may not have enough RAM. Read the following article.

See… Things you should know before updating your Mac OS

Updating non-Apple programs to their latest versions, may solve the problem. For instance Office 365.

Click on “Apple Symbol” > “Force Quit” and close any programs that have become unresponsive and see if this resolves the issue.


10. Slow Mac? – Battery is failing and needs replacing (MacBooks Only)

battery condition

A failing battery on a Macbook, Macbook Pro or Macbook Air or no battery at all forces the Mac OS to automatically under clocks itself so it runs slower when you're in the ‘red zone' of your battery. This is so you have ample time to save your and get to a charger. So if your battery isn't charging above 10-20%, it could be likely that it is the battery causing issues when running on battery power.

See… Macbook Battery Replacement Service

11. Slow Mac? – Too many programs trying to open upon startup

When your Mac starts up, it tries to open up programs that in the past you have requested startup on boot. Even if half these programs do not exist anymore.

Try cleaning out all these programs and restart the Mac, you should see a dramatic improvement in start-up speed.


remove mac login program


Use the minus key ‘-‘ to remove all login Items, click on the padlock to save the changes and then restart your computer.

12. Slow Mac? – Too many items on your desktop.

Some users save “EVERYTHING” on their desktop. Not a good idea.

When you Mac is starting up, it needs to create shortcuts and icons for each of these desktop items.

Move all those desktop items into a folder on your desktop and see the speed increase when starting up.

cluttered desktop



Slow/Problems with Internet/Browsing


  1. Browser Extensions need removingSlow internet browsing may occur if there are too many or illegal browser extensions, slowing performance.In Safari – Turn off or uninstall extensions- Choose “Preferences” from the Safari menu, then click “Extensions”.
    – Select an extension from the list.
    – Turn off the extension by deselecting the Enable checkbox.If you can't determine what an extension does, or you don't expect to use it again, click the Uninstall button.
  2. Virus or Malware (Mackeeper) or (CleanMyMac)See above, goto “Applications” and if you see any programs such as “MacKeeper” or “CleanMyMac”, uninstall them by dragging them to the trash.
  3. Browser Out of DateClick on “Apple Symbol” > “App Store” and check for any available updates for “Safari”, “Chrome”, “Firefox” etc.


Slow on Startup or will not start

See the following article… Why my Mac will not start.


Only by running a full Apple diagnostic, test and assess at our workshop (or by a qualified ) can you accurately identify the problem.  If you live in the Perth Metro area, bring your computer to our workshop in Subiaco and for :assess-fee: we can diagnose the problem and quote on a fix.


3 comments to “Why is my Mac Slow all of a Sudden?”

You can leave a reply or Trackback this post.
  1. Jim Demers - February 28, 2018 Reply

    High Sierra is a killer if you have an older Mac with a hard disk drive. The OS is optimized for SSD storage, and it will bog down terribly if I/O speeds aren’t what it expects.
    My 2012 MB Pro was nearly useless after the High Sierra update. I installed an SSD, and it came back to life spectacularly.

    • John Kirkby - March 2, 2018 Reply

      Wholly agree, although a brand new conventional HDD will also help rather than trying to use one a few years old. Also at least 8GB of RAM helps with caching.

  2. Joel - September 20, 2018 Reply

    I have ‘Adblock Plus’ as an extension. Is this slowing down my web browsing?

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