If you look like the cartoon in this site’s logo, completely perplexed at why your Mac is suddenly behaving the way it is, you have come to the right place!
We will look at some of the most common reasons why your mac is so slow all of a sudden, providing fixes as well!
Your Mac OS Partition Desperately Needs More Free Space
95% of the time, your Mac slows down to a crawl all of a sudden when your Mac OS Partition runs out of free space. It might not be full yet. But, since your Mac’s processor occasionally uses your Mac OS partition memory like how it uses RAM. When your Mac OS partition disk space is not at least 40% free, your Mac can decide to do the crawl. This will happen every time your Mac’s processor tries to access free space as memory. This is why you will notice that your Mac suddenly runs OK, only to suddenly start crawling again.
Thankfully, the fix is super simple. All you need is free disk space. Since you don’t want to go deleting important system files in your Mac OS Partition, it is much easier to use acclaimed software like Clean My Mac 3 to free up loads of disk space in your Mac OS Partition. Clean My Mac 3 is the third edition of the very successful Clean My Mac software that has been downloaded over 3 Million times since Clean My Mac Classic rolled out a few years ago. Since Clean My Mac can be scheduled to periodically clean your Mac from time to time, you will never have the problem of your Mac slowing down very suddenly in the future as well.
You made your Mac take on more OS than it could chew
If your Mac is suddenly slow right after an OS update, it could be that your Mac’s hardware just isn’t good enough to handle the new OS. For example, Mac OS Sierra is only recommended for Macs that were sold after 2009. If you tried installing it on an older system, you have no choice but to roll back to an older operating system like El Capital or Yosemite or even Mavericks.
However, if your hardware meets the minimum requirements for your OS but you are still having problems, all you might need is to reinstall your operating system. Yes, it is a boring chore and it sucks to do it twice, especially when you have just sat through a crawling installation. But, there’s no workaround to this. Grit your teeth and reinstall the OS and things will hopefully be back to normal.
Your Mac’s Disk Permissions have gone haywire
Your Mac is designed to control permissions for almost all files on your Mac’s OS X or OS. Sometimes, confusion prevails and your Mac can really slow down when an app or system file that needs to run is unable to do so because it isn’t granted permission.
Though it sounds like a very technical problem, the fix is as easy as clicking on a couple of buttons, thanks to the in-built repair disk permissions feature in your Mac.
To Access Repair Disk Permissions, go to (Only for Yosemite or OS Before Yosemite)
Applications -> Utilities -> Disk Utility -> Select OS X or OS partition -> Repair Disk Permissions
Don’t worry about running this utility even if there are no permission problems on your Mac’s hard drive. It won’t do any harm and can only fix potential problems.
Please note that the above path to repair disk permissions only works as long as you were using Yosemite or a predecessor OS. If you Mac OS Sierra, there is unfortunately no way to repair Disk Permissions. Apple have simply removed that option.
However, if you are still on El Capitan, you can repair disk permissions with the following two manual commands that you can enter in Terminal.
Manually repairing disk permissions in El Capitan
sudo /usr/libexec/repair_packages –verify –standard-pkgs /
sudo /usr/libexec/repair_packages –repair –standard-pkgs –volume /
Verify is to verify if permissions are OK while the repair command is to obviously repair permissions. You can just run repair straight if you wish. Please be sure to note down your OS X password as you will be prompted to enter it to successfully run the command.
Close terminal once process is finished.
Your Mac is Taking on too many things while booting up
Apps in your login list will load up automatically, every time you start up your Mac. So, if your Mac has suddenly started to slow down especially during the boot-up process, it could just mean that there’s just too many things happening in your login items.
Here’s how you access Login Items Tab
Go to System Preferences -> Account -> Login Items
Once there, take a list at the various apps that populate your Mac’s login process. Since any app is just one or two clicks away, there is no point making them all run in the background, as soon as your Mac starts to run. Keep only apps that you imperatively need to run right from the time you turn on your Mac and remove the rest. You will not only be speeding up your Mac’s boot-up, but will also be freeing up CPU and RAM resources at any point you use your Mac. To prevent apps from starting up at login, simply hit the “-” button next to the “+” button at the bottom of the Login Items window.
Your Mac’s UI is a little too fancy
Every Mac OS that comes out comes with improved UI elements. Commonly referred to as eye candy in the Apple community world, UI can be toned down to increase response times of your Mac’s OS X or OS.
To Access UI to tone it down,
Go to Apple Menu -> Accessibility -> Display Settings
Once there, you will see options to reduce transparency, tone down animation effects like the genie effect. Granted, toning down these settings will obviously mean that your UI is less pretty. But, the trade off in performance can make it well worth the sacrifice.
Your Mac has a rogue app that you can find and kill with Activity Monitor
Not all apps are always going to work very smoothly. If your Mac has suddenly become very slow, when you were using a particular app, it could very well mean that the app has crashed or become unresponsive, leading to a very, very slow Mac.
To quickly see if any such app is making life difficult for your Mac, go to Activity Monitor.
To access Activity Monitor
Go to Applications -> Utilities -> Activity Monitor
Run through the various tabs to see if you are able to spot any unusual activity. Pay particular attention to the CPU and Memory tabs. Ideally, no app should use up anything more than 5% of your CPU resource while no app should use up more than 100 MB of memory. If you are using a portable Mac like a MacBook Pro or MacBook Air, take a look at the energy tab as well, to see if an app is not just slowing your Mac but draining its battery very quickly as well.
After spotting a rogue app, you might have to force quit it. This might mean that you might lose any unsaved work that you might have carried out inside of the app. Make the decision wisely. If the work is important, give your Mac some time to pull itself together so you can save your precious work.
On the other hand, if the work is not that important or you just can’t handle your Mac being unresponsive anymore, force quit the app and watch your Mac jump back to life.
Apps that continuously appear as apps that consume high CPU% of RAM % are probably apps that are adware or malware. It is best you just uninstall them and not use them again. Sometimes, updating an app or reinstalling an app might also prevent the app from using too much CPU or RAM in the future.
Your Mac’s Browser needs to breathe
This tip is particularly helpful if your Mac’s internet or browser (Safari, Chrome or whatever you use) has really slowed down.
Press Command + Option + 2 when you have Safari open, or Command + H (for Chrome) and open up your History tab.
Here’ you will see an option to delete history, top sites, cached images, download windows and other items that you can reset. Depending on when you last cleared your history, if you have done it at all, your Mac’s browser can become very quick.
Just be careful to un-tick the “Remove saved names and passwords” box if you don’t want Safari or any other browser to forget your saved login and passwords for various sites that you frequent.
So, there you go! Why is my mac so slow all of a sudden? Hopefully you have found an answer to that question by now. If not, describe your problem more specifically in the comments below and we will do our best to give you a personalized solution.