MacOS High Sierra Slow? Top 10 Fixes

Top 10 Ways to Speed Up macOS High Sierra

Has upgrading to macOS High Sierra brought you nothing but performance issues? These top 10 fixes, listed in an order of priority of effectiveness, will have your Mac back up and running at normal speeds in no time. Try these fixes in order to eliminate macOS High Sierra slow problems in a matter of minutes.

1.Let your hard drive breathe!

Not a lot of people know this but your Mac’s processor very often relies on hard disk space to compute various things. In other words, it’s not just your Mac’s RAM that acts as memory. Your Mac’s hard disk is like secondary RAM to your Mac. When your hard drive is full or even just choked up to 80%, your Mac is invariably going to run slowly.

In fact, beyond a certain point where your hard drive is full of too much data, your Mac can begin to crawl or even freeze up for no reason, while you are doing something as simple as typing out a Pages document.

The fix however is very easy. All you have to do is free up a lot of data by either deleting unwanted data or by moving out data to an external hard drive or a partition on which your mac OS High Sierra isn’t installed on.

Clean My Mac 3If you want to do this the super easy way, all you have to do is use a software like CleanMyMac 3, which will clean up massive amounts of space like 40 or 50 GB in a matter of minutes, with just a couple of clicks of your mouse!

Try CleanMyMac 3 and you will be surprised at how quickly and easily it makes your macOS High Sierra work fast and smooth.

Clean My Mac 3 is available for a FREE download here.

2. Leverage macOS High Sierra’s Optimize Storage Function

This is kind of what CleanMyMac 3 does, but not just as effectively. But, the good thing is that this is rolled out by Apple as an in built feature into High Sierra. All you have to do is turn it on.

macOS High Sierra Optimize Storage

Optimize storage on your hard disk using High Sierra’s inbuilt storage optimization. Not as effective as CMM 3 but good to have!

By turning on the Optimize checkbox, your Mac will constantly clean up free hard disk space where it can, in small bits and pieces. It will remove certain data from your Mac’s local hard drive and upload it to your iTunes Cloud account. This way, you don’t lose the data and you also don’t valuable hard disk space on your Mac.

You will always receive notifications about which file is being deleted, moved to the Cloud. Since you are notified, you can always control what is being moved or deleted. Using this function will mostly prompt your Mac to get rid of things like old files that you haven’t touched in a very long time, mail attachments, fonts that you never use and certain other system files that are just redundant on your Mac.


macOS High Sierra is out! The brand new OS designed to make your Mac more reliable, responsive and capable should be giving you a fantastic new experience. The all new OS uses state of the art 64 bit architecture to organize how your data is stored and retrieved, to give you a smooth user experience. Video streaming is particularly improvised in this version of macOS High Sierra, since your Mac will now use the full power of your graphics processor as opposed to tapping into your core processor’s capabilities.

But, what good are all these promises if your Mac is just facing issues after your recent upgrade to macOS Sierra. Your Mac should be faster, more responsive and more fluid, not slower! If you are facing the dreaded macOS High Sierra slow problem just after your upgrade to the new OS, here are simple but sure shot solutions that will help you fix your slow and unresponsive Mac. Applying these tips will ensure that your Mac runs butter smooth, like it is supposed to, when you have just upgraded to a brand new OS.

Let’s now continue this tutorial with the remaining 8 tips that will allow you to troubleshoot your new OS problems. Please remember that these tips are given out to you in order of priority that factors ease of applying the fix. In other words, the tips at the beginning are the easiest to carry out, to fix your macOS High Sierra Slow.

Top 10 Fixes to Fix macOS High Sierra slow problems continues below!


3. Shut down rogue apps

Sometimes, it could be that your Mac just needs a break from apps that have malfunctioned. If your Mac is running very slowly after you have run certain applications, simply shutting down such applications can help you speed up your Mac.

To see if any applications have gone rogue or are taking up too much space, do a quick check on your Mac’s Activity Monitor. It is really easy to do.

Just go to Applications -> Utilities -> Activity Monitor. Once in there, you will see a populated list of all the apps that are running on your Mac, with details on how much CPU and RAM resources they are taking up, like shown below.

Check Activity Monitor in Utilities to find rogue apps that are making your Mac crawl

If you see anything taking up a significant amount of CPU or memory resources, it probably means that the app has crashed, frozen or is holding down your Mac in an unfair manner. If you find such rogue apps, simply shut them down and your Mac might spring back to life. This is actually one of the most powerful ways to fix macOS High Sierra slow problems. Of course, please remember that shutting down such apps through Activity Monitor will mean that you might lose unsaved data that you had created through the app. So, take a moment before you force quit any app, especially if the content you were creating took a lot of time to create. If you do not wish to force quit a rogue app, your only other choice is to stop doing everything else on your Mac, giving it all the resources it needs to make that rogue app work properly, so you can save your work and then shut it down.

4. Scale Back High Sierra UI Fanciness

This isn’t really an ideal tip to follow. After all, when you install a new OS like High Sierra, you want to see what UI improvements have been made. You want to enjoy things like animations and what not when you close and open windows. But, sometimes, Apple’s UI tweaks to a new OS don’t work well until they roll out an update to their newly launched OS.

If there’s a bug in the way the UI eye candy works, it can tremendously slow down your Mac.

macOS High Sierra reduce motion and transparency

Reducing High Sierra’s UI fanciness can fix your slow performance issues

To turn off the UI eye candy, all you have to do is go to system settings and then go to accessibility and then the Display option. Once there, reduce as many UI eye candy features as possible. Some of the features you can disable are by reducing motion and transparency.

5. Don’t Choke Your Mac with a Ton of Startup Items

Whether you know it or not, you might be making your Mac take on a ton of work as it starts up after a restart or a fresh start. In case you did not know, you can make your Mac automatically load programs in the background as soon as it starts up. While this offers convenience, having too many items in this startup or login list can lead to macOS High Sierra slow login and boot times.

Since any app can be called up in a few seconds, it is unnecessary to have any items in your login list at all. You must at the most have only 1 or 2 items in this list. Delete all the other apps from the login list and your Mac will thank you for it.

High Sierra Login Items Editing to Speed Up Mac Login

Edit your High Sierra’s login list to help High Sierra load and boot faster

This is a fix that you must particularly try if your Mac and High Sierra is particularly slow when you just start it up. To edit your login list, go to System Preferences, then Users and Groups, find your user and then go to Login Items. Once there, use the minus sign to remove apps that you don’t need to start up as you start your Mac and High Sierra. Once again, try to keep this list down to 0, 1 or just 2 items at the most. Edit this list and restart your Mac and you will be amazed at how quickly it boots.

6. Consider upgrading to an SSD

If you are using a Mac that can run High Sierra, it probably means that you already have an SSD on your Mac. If not, you must seriously consider this upgrade that can make a world of a difference to your Mac’s speed, especially with High Sierra.

SSD for your Mac to speed up High Sierra

Install a SSD on your Mac to let High Sierra run much faster than it does now.

A SSD is many times faster than a traditional hard drive as it does not have any moving parts. It is completely digital. In a regular hard disk, the disk spins and a spindle retrieves data from various locations on the hard disk. All the spinning takes time and resources that make it slow. On a SSD however, information is retrieved in a fraction of the time it takes to retrieve information from a traditional hard disk, resulting in much faster operating times.

Remember, when you get an SSD, you must install your macOS High Sierra on the SSD. Try to get an SSD with as much capacity as possible as the more free disk space you have on your SSD, the faster your Mac will be.

If you can afford a hardware upgrade, this is one of the best ways to address macOS High Sierra slow speed issues.

7. Make use of High Sierra’s iCloud Storage Function

Ever since Sierra came out, Apple has given you an option where you can send your Mac’s data that you only occasionally use to the iCloud. Besides helping you free up space on your Mac’s hard drive, storing data on your iCloud allows you to access it anywhere, even from other Apple devices, as long as you have the same iTunes account.

iCloud storage in High Sierra

Enabling iCloud Storage in High Sierra allows for free disk space that can speed up the macOS

Just be a little wary of iCloud storage’s algorithm that sometimes decides that some files on your Mac are just not necessary to store anymore. In such cases, it will just go ahead and delete these files. This may not work for you. In such cases, you can still use iCloud by performing backups on external hard drives as well. This will require you to carry out an extra step of course.

8. Reset System Controllers like SMC and PRAM

Resetting your Mac’s SMC or PRAM are called soft resets. What this means is that no user or important system data is deleted. These resets instead just reset the connections between your Mac’s software and hardware, which can sometimes surprisingly speed up your Mac.

For example, an SMC reset will fix any battery issues that you have on your Mac notebook, if such issues pertain to your High Sierra’s organization or monitoring of your battery. On the other hand, a PRAM reset will fix issues pertaining to High Sierra’s screen resolution, boot issues and battery charge cycle issues.

As you can imagine, a fix to any of these issues can help you overcome performance issues with your Mac running on High Sierra.

Please see this Apple resource for detailed instructions on how to reset SMC and PRAM on your Mac desktop or notebook.

9. Download and Install Patches to High Sierra, if Available

Sometimes, a macOS High Sierra slow issue will not have anything to do with your Mac at all. It could just be that the OS has bugs that prevent your Mac from running normally. In such cases, all you can do is download the patches or updates that Apple releases, to fix these kinds of issues.

To check if there are patches available, simply head over to the App store and check for software updates for High Sierra. There might not be one always available but if it is, it will almost always fix performance issues for you.

It might also be a good idea to turn on automatic updates for your Mac’s OS. You will still be prompted before an upgrade but you will atleast immediately know when an update or patch is available, via a prompt on your Mac’s screen.

10. Maybe your Mac can’t run High Sierra!

Sometimes, it could just be that you just jumped the gun when it came to installing macOS High Sierra when your Mac just isn’t capable of running the new OS.

If your Mac is not among the models mentioned below, you will unfortunately have to roll back to an older Mac OS like Sierra, El Capitan or even older OS versions, depending on your Mac’s age.

Macs that are compatible with macOS High Sierra

iMac – Only iMacs bought in late 2009 or after

MacBook – Only MacBooks bought in late 2009 or after

Mac Pro – Only Mac Pros bought in 2010 or after

Mac Mini – Only Mac Minis bought in 2010 or after

MacBook Air – Only MacBook Airs bought in 2010 or after

MacBook Pro – Only MacBook Pros bought in 2010 or after

To conclude this post on helping you fix your slow performance issues on your Mac running High Sierra, we will say that using CleanMyMac 3, upgrading to an SSD and freeing up disk space on your Mac’s hard drive will all give you guaranteed speed up results.

The other tips may or may not work, depending on whether it is an issue in the first place. But, in any case, a combination of these 10 tips should allow you to fix your macOS High Sierra slow issues one way or another.

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