Is Your Mac Slow After Upgrading to macOS High Sierra? Here‘s How to Fix It

In September 2017, Apple released macOS 10.13 High Sierra, a major update to the operating system for Mac computers. High Sierra introduced new core technologies and refined the user experience from previous versions. Key features included the new Apple File System (APFS), Metal 2 graphics technology, and significant updates to apps like Photos and Safari.

However, as with most major OS updates, some users experienced slowdowns and decreased performance after upgrading to High Sierra. Common issues included longer boot times, sluggish performance, unresponsive apps, and visual glitches.

If you‘ve noticed your Mac running slower after updating to macOS High Sierra, don‘t worry – in most cases there are simple explanations and solutions to get your machine running smoothly again. In this article, we‘ll cover the most common causes of performance issues in High Sierra and provide step-by-step troubleshooting to address them.

Common Causes of macOS High Sierra Running Slow

There are a few frequent reasons why your Mac may feel more sluggish after upgrading to High Sierra:

Lack of free disk space – High Sierra requires adequate free space on your startup disk in order to run well. Aim to keep at least 15-20GB free if possible. Low disk space can cause slowdowns and instability.

Too many startup/login items – Having a large number of applications set to automatically launch when you log in can significantly increase boot time and consume system resources. Disable unnecessary startup items for better performance.

Outdated software and incompatible apps – Older versions of applications not optimized for High Sierra may run slowly or cause other apps to hang. Make sure you have the latest versions of all software and contact developers about any incompatible apps.

Spotlight re-indexing – After a major OS update, Spotlight search may need to re-index all the files on your hard drive which can temporarily degrade performance, especially on older Macs. This process can take hours or even days to complete.

Hardware limitations – macOS High Sierra dropped support for some older Macs and its higher system requirements mean it may run slowly on the minimum specifications, especially if you have an HDD rather than an SSD. 8GB or more RAM is ideal.

SMC and NVRAM issues – Rarely, the System Management Controller or non-volatile RAM can become corrupted during an OS update which may cause hardware and performance bugs until reset.

Now that we‘ve covered the common culprits, let‘s dive into troubleshooting and fixes for each scenario.

Troubleshooting and Fixing macOS High Sierra Slowdowns

Follow these steps in order to diagnose and resolve the specific cause of your performance issues:

Free Up Disk Space

Click the Apple logo in the top-left corner and choose "About This Mac". Select the Storage tab to see an overview of your disk space usage. If your startup disk is more than 85% full, you‘ll want to delete some files to free up space:

• Move large files like videos and archives to an external drive or cloud storage service
• Uninstall apps you no longer use by dragging them to the Trash
• Use the built-in macOS storage management tools under "Recommendations"
• Consider doing a clean install of High Sierra if your disk is nearly full

Disable Unnecessary Login Items

Go to System Preferences > Users & Groups and select your user account. Click the Login Items tab to view the list of apps that automatically start when you log in.

Highlight any items you don‘t need and click the "-" button below the list to remove them. Be careful not to disable anything important or system-related.

Update All Software

Open the App Store and click the Updates tab. Install any available updates for macOS as well as individual apps. Relaunch any apps that were updated.

For software not downloaded from the App Store, visit the developer‘s website to download the latest versions compatible with High Sierra. If you have any mission-critical apps, check with the developer to verify High Sierra compatibility before upgrading.

If any of your applications are incompatible with High Sierra and there are no updates available, you may need to find alternative programs to use instead. Continuing to run incompatible software can cause slowdowns and instability.

Wait for Spotlight Indexing

After upgrading to High Sierra, the Spotlight search engine needs to re-index all the files on your startup disk. You‘ll see a progress bar in the Spotlight menu in the top-right corner while indexing is underway.

This one-time process can take a long time and consume CPU cycles, so your Mac may feel slower until it finishes. If you have a large hard drive or a slower Mac, it can take a day or more to complete indexing. For the best performance, let your machine idle without using it heavily until indexing is done.

Disable Visual Effects

If your Mac is an older model, you can speed things up by disabling some of the eye-candy visual effects in macOS:

• Open System Preferences and click Dock
• Uncheck "Magnification", "Animate opening applications", and "Automatically hide and show the dock"
• Click Minimize windows using and change Genie effect to Scale effect
• Select Accessibility, then Display, and check "Reduce motion" and "Reduce transparency"

Disabling these animations and graphical effects can make the user interface feel more responsive on slower hardware.

Reset the SMC and NVRAM

If you‘re experiencing hardware-related issues like problems with your fans, battery, or keyboard, resetting the SMC might help:

• Shut down your Mac and plug it in if it‘s a laptop
• Press and hold Shift + Control + Option and the power button for 10 seconds
• Release all the keys and wait a few seconds
• Press the power button again to boot up your Mac

If you‘re having boot problems, display issues, or problems with volume and time settings, you can reset the NVRAM as well:

• Shut down your Mac completely
• Press the power button and then immediately hold Option + Command + P + R
• Keep holding until you hear the startup sound a second time, then release the keys
• Let your Mac finish booting up

More Tips to Optimize macOS High Sierra Performance

Here are some additional suggestions to keep your Mac running in tip-top shape on High Sierra:

Enable automatic updates – Make sure automatic updates are enabled for macOS and App Store apps to receive performance improvements and bug fixes as soon as they‘re available.

Restart regularly – Rebooting your Mac clears out temporary system files and stops background processes from consuming memory over time. Aim to restart at least once a week for the best performance.

Keep an eye on Activity Monitor – Launch Activity Monitor in your Applications folder to view statistics about CPU, memory, energy, and disk usage on your Mac. Watch for apps that are hogging resources and close them if possible.

Install an SSD – If you have an older Mac with a slower hard disk drive, upgrading it with a solid-state drive can give an incredible boost in speed, especially for booting up and launching apps. An SSD is the single best upgrade you can make for an older machine.

Add more RAM – Like an SSD, upgrading your Mac with more RAM can greatly improve performance and allow you to multitask with demanding apps more smoothly. 8GB of RAM is the minimum you want for High Sierra.

What About Future macOS Updates?

As of September 2018, Apple has released the next major version of its desktop operating system in the form of macOS 10.14 Mojave. Mojave builds upon High Sierra with some major new features like a system-wide dark mode, desktop Stacks, a redesigned App Store, and enhanced security and privacy protections.

Mojave also promises improved performance and bug fixes, but inevitably some users may experience slowdowns or software incompatibilities, especially on older hardware. If you rely on your Mac to get work done, it‘s prudent to wait at least a few months before upgrading to the latest OS to give Apple time to iron out kinks and optimize performance.

By following the troubleshooting steps and optimization tips in this article, you should be able to resolve most causes of slowdowns and get back to enjoying the new features of macOS High Sierra. Remember that the first few days after a major OS update are often slower as Spotlight re-indexes and things settle in, so be patient during the transition period.

The Bottom Line

Upgrading to a new version of macOS is exciting, but it can be frustrating if your Mac feels slower afterwards. If your machine seems sluggish after updating to macOS High Sierra, don‘t panic – in most cases there are straightforward reasons and fixes that can restore it to tip-top shape.

Lack of disk space, too many startup apps, outdated software, and Spotlight re-indexing are common culprits for temporary slowdowns after an OS upgrade. You can address these issues by freeing up storage, updating your apps, being patient with Spotlight, disabling animations, and resetting the SMC and NVRAM if needed.

For the best performance, consider upgrading your Mac with an SSD and more RAM, and always keep automatic updates enabled. By optimizing your machine and being prudent about future updates, you can enjoy the latest and greatest macOS features without sacrificing the speedy, responsive experience you expect from your Mac.