High Sierra Mac Slow Fix Tips

Having a slow Mac can be frustrating, especially when you rely on it for work or personal use. In this article, I will share some valuable tips to fix the slow performance issue specifically on High Sierra Macs.

Check Compatibility and Optimize Storage

To fix your slow Mac running on macOS High Sierra, it’s important to ensure compatibility and optimize your storage. Here are some tips to help you speed up your Mac:

1. Check Compatibility:
– Make sure your Mac is compatible with macOS High Sierra. Check the system requirements on Apple’s website to confirm compatibility.
– Update your Mac’s software to the latest version. Go to the Apple menu > Software Update and install any available updates.

2. Optimize Storage:
– Clear out unnecessary files and folders. Use the Trash to delete files you no longer need.
– Clean up your hard disk drive by removing large files and old applications.
– Utilize the iCloud storage service to store files and free up space on your Mac.
– Use the Apple Mail app to manage and delete old email attachments to free up storage.
– Consider upgrading to a solid-state drive (SSD) for faster performance and better storage management.

Clean and Decongest Hard Drive

Hard drive with a cleaning brush.

To clean and decongest your hard drive on High Sierra Mac and fix slow performance issues, follow these simple steps:

1. Remove unnecessary files and applications: Start by deleting any files, folders, or applications that you no longer need or use. Empty your Trash to permanently remove them from your hard drive.

2. Clear cache and temporary files: Cache and temporary files can accumulate over time and take up valuable space on your hard drive. Use a cleaning tool like CleanMyMac X to safely clear out these files and free up storage space.

3. Organize your files: Take the time to organize your files into appropriate folders and delete any duplicates. This will not only help you find files more easily but also create more space on your hard drive.

4. Optimize your storage: High Sierra Mac offers a feature called “Optimize Storage” that automatically removes TV shows and movies you’ve already watched, as well as old email attachments. To enable this feature, go to Apple menu > About This Mac > Storage > Manage > Recommendations.

5. Move files to the cloud: Consider moving large files or folders to iCloud to free up space on your hard drive. Drag and drop files to iCloud Drive or use the “Optimize Mac Storage” option to automatically store older files in iCloud.

6. Uninstall unnecessary applications: Review your installed applications and uninstall any that you no longer use or need. Go to the Applications folder, select the application, and drag it to the Trash.

7. Disable unnecessary startup items: Some applications may automatically launch at startup, slowing down your Mac’s performance. Go to System Preferences > Users & Groups > Login Items and uncheck any applications that you don’t need running at startup.

8. Check for software updates: Keeping your Mac up to date with the latest software updates can improve performance and fix any bugs or issues. Go to the Apple menu > System Preferences > Software Update to check for and install any available updates.

9. Restart your Mac regularly: Restarting your Mac can help clear out temporary files and refresh system resources. Go to the Apple menu > Restart to give your Mac a fresh start.

10. Consider upgrading your hardware: If your Mac is still running slow after following these tips, it may be time to consider upgrading your hardware. Adding more memory (RAM) or replacing your hard drive with a solid-state drive (SSD) can significantly improve performance.

Reduce Visual Effects and Background Applications

To speed up your High Sierra Mac, it’s important to reduce visual effects and background applications that may be slowing down your system. Here are some tips to help you do that:

1. Disable Visual Effects: Visual effects may look appealing but can consume a lot of CPU time and memory. To disable them, go to System Preferences > Accessibility > Display. Uncheck the “Reduce motion” option to minimize animations and effects.

2. Close Unnecessary Applications: Having too many applications running in the background can slow down your Mac. Close any unused applications by clicking on the application name in the menu bar and selecting “Quit” or by using the shortcut Command + Q.

3. Manage Startup Items: Some applications automatically launch when you start up your Mac, consuming valuable system resources. To manage startup items, go to System Preferences > Users & Groups > Login Items. Remove any unnecessary applications from the list by selecting them and clicking the “-” button.

4. Clean up Your Hard Drive: A cluttered hard drive can significantly slow down your Mac. Use the CleanMyMac X application to scan for and remove unnecessary files, duplicate files, and system junk that is taking up valuable disk space.

5. Disable Background Processes: Some applications run background processes that can impact your Mac’s performance. To check and disable these processes, go to Activity Monitor (Applications > Utilities > Activity Monitor) and look for any processes consuming a high percentage of CPU or memory. Select the process and click on the “X” button to quit it.

6. Optimize Mail Settings: Apple Mail can consume a lot of system resources, especially if you have a large number of email accounts or a large mailbox. To optimize Mail settings, go to Mail > Preferences > Accounts and disable unnecessary accounts or set them to only sync manually.

7. Limit Visual Effects: High Sierra offers various visual effects, such as transparency and motion, that can impact performance. To limit these effects, go to System Preferences > Accessibility > Display. Check the “Reduce transparency” and “Reduce motion” options to minimize the visual effects.

8. Keep Software Updated: Make sure you have the latest version of macOS High Sierra and all your applications. Updates often include performance improvements and bug fixes that can help speed up your Mac.

Upgrade Hardware and Reconfigure System Settings

To improve the performance of your High Sierra Mac, consider upgrading your hardware and reconfiguring your system settings. These tips will help you optimize your Mac for better speed and efficiency.

1. Upgrade your hardware:
– If your Mac is running slow, consider upgrading your RAM. Adding more RAM can significantly improve your Mac’s performance, especially when running memory-intensive applications. Check your Mac’s specifications and purchase compatible RAM upgrades.
– Another hardware upgrade to consider is replacing your hard drive with a solid-state drive (SSD). SSDs are faster and more reliable than traditional hard drives, and they can greatly improve your Mac’s boot time and overall responsiveness.

2. Reconfigure system settings:
– Adjust your energy saver settings to optimize performance. Go to the Apple menu > System Preferences > Energy Saver and choose the “Better Performance” option. This will prevent your Mac from entering sleep mode too quickly and ensure that it’s always ready for action.
– Clean up your desktop and remove unnecessary icons. Having too many icons on your desktop can slow down your Mac’s performance. Organize your files into folders and move them off the desktop to free up system resources.
– Disable unnecessary startup items. Some applications launch automatically when you start your Mac, which can slow down the boot process. Go to System Preferences > Users & Groups > Login Items, and remove any unnecessary apps from the list.
– Clear out system junk and temporary files. Over time, your Mac accumulates various temporary files that can take up valuable disk space and slow down performance. Use a reliable cleaning tool to scan and remove unnecessary files from your Mac.
– Reset the SMC (System Management Controller) and PRAM (Parameter RAM). These system controllers store various settings related to power management, hardware, and more. Resetting them can help fix certain performance issues. Refer to Apple support documentation for instructions on how to reset the SMC and PRAM for your specific Mac model.

By upgrading your hardware and reconfiguring your system settings, you can significantly improve the speed and performance of your High Sierra Mac. These tips will help you get the most out of your Mac and enjoy a smoother computing experience.


What is the oldest Mac that can run High Sierra?

The oldest Mac that can run High Sierra is the Late 2009 iMac or the Late 2009 MacBook.

Why is my Mac so slow and laggy all of a sudden?

Your Mac may be slow and laggy all of a sudden due to several reasons. These include an outdated operating system or a full hard disk, particularly if you have an older Mac model. If your Mac is new, it could be slow because you are running too many background programs and apps or have a malware infection.

How can I speed up my MacBook Pro High Sierra?

To speed up your MacBook Pro High Sierra, you can clean up your hard drive. Removing unnecessary files and applications that are slowing it down will give you the most noticeable improvement in performance.

How do I optimize my High Sierra?

To optimize your High Sierra, you can start by updating your software, tidying up your start up, cleaning out unused apps, clearing out the downloads folder, organizing your storage disk, cleaning out the cache, removing resource-hungry programs, and emptying the trash.

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