If Disk Utility reports “The underlying task reported failure”, try to repair the disk or partition again. If Disk Utility says the disk appears to be OK or has been repaired, you are good to go.

Click the “First Aid” button, and then “Run”.

You'll see the available disk listed in the sidebar.Select “Disk Utility” in the “macOS Utilities” screen, then click “Continue”.After your Mac restarts, press and hold the Cmd+R keys until you see the Apple logo.This native macOS application can fix various problems such as the ones listed above. If some of the above apply or your computer doesn't start up, begin fixing your disk by using the built-in Disk Utility. If you have noticed that multiple apps have quit unexpectedly, files have become corrupt or an external drive doesn't operate properly, it's possible you have problems with your hard or flash drive, which is why macOS is running slow. When you click on the quit process, a pop-up will ask you whether you want to “Force Quit” or “Quit” the process.Click on the X button located in the top-left, along with the “Information” and “Settings” buttons.You should force macOS to quit any processes that are using too many processors resources: Use a Monitoring Appīut whenever you feel that your Mac is running slow, just launch Activity Monitor (pro tip: type “activity monitor” in Spotlight), and under the CPU tab check which apps are using a high level of CPU resources.

Of course, it's also recommended to have a clean desktop because a cluttered desktop with hundreds of files of different sizes will slow down your Mac.

Check the boxes “Reduce motion” and “Reduce transparency”.

Select “Display” from the left set of menu items.

Launch System Preferences and hit Accessibility.

Turning these features off is especially useful for improving the performance of your Mac if you are constantly using lots of apps or have a lot of open windows. The problem with this feature, however, is that in the long term it could lead to performance issues as each new window requires more and more system resources, first to draw and then to maintain. MacOS includes design features that are easy on the eye, such as transparent windows. Clean 500MB of Junk for Free Reduce Transparency

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