Is your Mac slow after the High Sierra update? You've come to the right place. We think we have the best advice out there to speed up your under performing Mac running High Sierra. We'll make sure to update this page when we run into new fixes.

Mac Running Slow After High Sierra? Fixes for your computer:

Free memory = Faster High Sierra

Past macOS installs were very RAM hungry. macOS High Sierra is an updated version of Sierra, so it too is very RAM hungry. 4GB or 8GB of RAM might not be enough depending on what you're doing with your computer.

There is a very simple fix: you'll need to free up memory space on your computer. Though there are manual ways to do this, but we would recommend that you use software like CleanMyMac 3 to handle the task. CleanMyMac 3 is an excellent piece of software to handle basic system maintenance on your Mac.

CleanMyMac 3 is available for download here.

Repair Disk Permissions in macOS

In some cases, repairing disk permissions can help speed up your slow mac after the High Sierra update. To repair your disk's permissions, simply follow the steps below.

Restart your Mac

Press the "Option" key as soon as you hit restart

When prompted, select "Disc Utility Option"

Select the partition where you previously installed macOS High Sierra

Click "Fix Disc Permissions"

Restart your Mac normally

This should have an effect on the speed of your computer.



Run Mac System Resets in High Sierra

For some people, simply performing a SMC and PRAM reset can help fix performance issues, even if they aren't tied to a system upgrade.

The System Management Controller is a piece of hardware in your computer that coordinates battery and heat management, LED lights, and other parts of the hardware. PRAM (Parameter RAM) stores the default values of some core system settings such as your alarms, mouse settings, start up programs, and speaker volume. Sometimes these two parts of the computer can get bogged down and slow down the rest of the system.

We have provided instructions on how to carry out these resets in a post about fixing MacBook Pro's performance issues. The post talks specifically about MacBook Pros, but the instructions will work for any Apple computer.

Re-install macOS High Sierra

Yes, we know that this isn't an ideal resolution to your problems, but this might just be your last resort to fix performance issues from High Sierra.

How do you re-install macOS High Sierra?

Restart your Mac

As your Mac restarts, hit ⌘ (command) + R, together

When prompted, choose and connect to your choice of Wi-Fi network

Select option called Re-Install macOS High Sierra

Re-Install macOS High Sierra on the same OS X Partition that you previously installed it on

Wait it out (It can take several hours, so take this into consideration)

Restart after the re-installatio

Try to set this process up before you go to sleep for the night so you can wake up to a computer running quickly and smoothly.

Fixing slow WiFi speeds after the macOS High Sierra update

We have received several comments that say that their Mac's Wi-Fi has either stopped working or has been reduced to a crawl after the macOS update.

How can you fix High Sierra related Wi-Fi issues on your Mac?

Try deleting a certain System Configuration file

Finder -> Go -> Computer -> Macintosh HD -> Library (double click) -> Preferences (double click) -> Find file called "SystemConfiguration" -> CMD + DEL -> Enter password if necessary -> Restart your Mac

Altering Keychain Access

Keychain Access -> System -> Wireless Network -> Double Click -> Access Control -> Check "Allow all applications to access this item"

Turn off bluetooth

Apparently, just turning off Bluetooth allows the Wi-Fi connection to work normally for some people. Sometimes High Sierra is struggling to keep both a Bluetooth and Wi-Fi connection running at the same time.

Create new network location

Network Preferences -> Location -> Create a New Location -> Enter a New Name -> Hope for normal Wi-Fi!

Turn off Handoff

Setting -> General -> Turn Off Handoff

Altering network preferences

Network Preferences -> Wi-Fi Adapter -> Click on the "cog" or setting wheel icon at the bottom -> Make Service Inactive -> Apply -> Click on Wi-Fi in the same list-> Click (-) to delete -> Apply -> Reboot your Mac -> Network Preferences -> Wi-Fi Adapter -> Click (+) -> Select Wi-Fi from dropdown list -> Change the name of the Wi-Fi network (IMPORTANT, Must change!) -> Apply -> this should fix your problems

If you find High Sierra slow even after these fixes, let us know about that as well. We're always wanting to improve our content.

Turn Off Transparency Effects

Some users have said that this tiny tweak can make a huge performance difference for a High Sierra-based computer.

Simply head over to the Apple Menu -> System Preferences -> Accessibility -> Display -> Check the box that says "Reduce Transparency".

This lowers High Sierra's visual appeal, but it also reduces the general load on your system's resources.

Lighten up the Notification Center Workload

By default, High Sierra loads up calculator, weather, stocks, social, and reminder notifications, requiring some extra system resources that could go towards other applications.

Go to the Apple Menu -> System Preferences -> Extensions - Today, and then disable widgets that you don't use.

Turn Off File Vault Encryption

Decrypting your hard drive, though not exactly ideal, is another way to speed up macOS High Sierra. If you had enabled File Vault during your High Sierra installation, you can reverse this decision now.

Go to the Apple Menu -> System Preferences -> Security & Privacy -> Enter Administrator password if prompted -> Turn Off File Vault -> Turn Off Encryption -> Restart Mac

Throttling back Spotlight

Spotlight in High Sierra is powerful, exciting, and refreshingly new. However, if you are running it at full speed there is a chance that it might be making your Mac's processor and RAM bite off more than it can chew and slow down the system.

To throttle back the performance of Spotlight, go to System Preferences -> Spotlight -> Un-check categories as needed.

For example, if you don't need Spotlight to look up web definitions for every search, simply disable "Definition". You might also feel that search results from calculator, system preferences, and even documents might be unnecessary. For every category that you turn off, Spotlight has to do a little less work, which should speed up your computer.

Turn off Dashboard

Dashboard in High Sierra is fun and exciting but it can decrease system performance, especially related to graphics. Once again, if you don't mind losing some eye candy to fix your performance issues, you can definitely try turning off Dashboard altogether.

Go to System Preferences -> Mission Control -> Set Dashboard setting to Off.

Fixing other High Sierra related performance issues on your Mac

Unreasonable battery drain

Turning off transparency

Turning off transparency effects also seems to help with battery drain issues.

Go to System Preferences -> Accessibility -> Reduce Transparency. This can be a good trade off, because all you'll be losing is a bit of visual flair. After all, what good is a flashy UI if the battery doesn't last long enough for you to get work done on your computer?

It's worth mentioning-- sometimes these battery issues are related to your system having to work harder after a new instillation, so they might clear up on their own after a day or two.

Safari slow on High Sierra

Clearing cache

Try clearing the Safari cache to see if your browsing will speed up afterwards. Sometimes the cache can become bloated and slow down your browsing experience.

To clear your Safari cache, go to Safari -> Preferences -> Privacy -> Remove all website Data. If you have never cleared out your cache before, this might significantly speed up internet browsing.

The whole idea of browser caching is to actually help speed up your browsing experience. Your browser downloads small objects like logos from websites that you visit often, and they'll load back up the next time you visit the site. However, beyond a certain point, excessive caching can actually lead to problems as there might just be too much locally downloaded content that doesn't sync up with websites that are continually modified or updated on a daily basis.

Clearing Finder

Open Finder -> Go -> Go to Folder

Now, type in the following line exactly as given. ~/Library/Caches/com.apple.safari/cache.db

Once Finder finds the file for you, click it and delete it by moving it to trash. Once done, restart Safari to see if browsing is faster.

Turning off Safari Extensions in High Sierra

Though some Safari extensions can make browsing very convenient, they can slow down your browsing experience significantly, especially when they don't get along with the latest version of your operating system.



This might be too much for some people, but if you want to turn off extensions simply go to Safari -> Preferences -> Extensions -> check the toggle button at the top-right-> Restart Safari

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Drop us a comment with your own fixes and questions as well, and we'll add it to the list if we think it'll be worth other people seeing. We would love to publish your comment for all to see.

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