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How to Clean Up and Optimize Your Mac

Optimize Your Mac

Got a Mac that’s getting slower and slower? Do a quick cleanup to free up storage space by deleting files and applications that fill it up quickly.

Do you have the impression that your Mac no longer works properly, that it reacts slowly to every request?

Don’t think that it no longer works: it is perfectly normal for Mac performance to degrade somewhat over time, especially as applications and the operating system tend to consume more and more resources.

How to clean a Mac

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However, a generalized slowdown often has another very classic cause: memory saturation, i.e. the hard disk or the main SSD of your Mac, which prevents its normal operation.

A thorough cleaning of the programs is all that is needed to bring it back to like-new condition.

It’s easy to get started – and regularly! – with the tools built into macOS, but you can also use specialized tools for more delicate tasks.

Why does a Mac become slow over time?

Whether it is a Mac or a PC, all computers use two types of memory: random access memory (Ram) and storage memory (hard disk, SSD, USB, flash card, etc.).

They differ in their capacity, speed and the way they retain the information entrusted to them.

RAM is a temporary working memory that holds everything the processor needs to run, to have the operating system (MacOS in the case of a Mac), applications and items that are opened (documents, images, web pages, etc.).

It is very fast, but “small” in size (typically 4 to 16 GB) and therefore limited. Above all, it loses its content as soon as it stops receiving power.

Storage memory is a storage memory. Large in size (typically a few hundred gigabytes to several terabytes), it contains everything you need to store your data.

store (operating system, applications and personal files) permanently, even without power supply.

But it is slower than random access memory, although the chip technology used in SSDs is significantly faster than the mechanical technology used in traditional hard drives.

These two types of memory are complementary. When you turn on your Mac, part of the macOS system is copied from storage memory to RAM to work quickly.

The same happens every time you launch an application, as it moves from storage memory – where it patiently waits its turn – to RAM to be used on your Mac.

As you launch the applications you need and the tasks you ask them to perform, the storage memory of the MAC starts to become saturated very quickly.

When this critical point is full of information, it uses part of the hard disk to temporarily offload some lower priority tasks (using the so-called swapping technique).

For example, if you open many tabs in your browser, then the Excel program that you have not touched for half an hour may be encouraged by the consumption.

This then explains on the screen certain delays that sometimes occur when you return to an application that you had left untouched for a long time.

As you can see, that’s where the bottleneck is: if there’s no more space on the hard drive either, the Mac is lost.

It spends its time transferring small chunks of data from one memory to another as needed, and ends up spending more time making those transfers.

Not to mention that, if the hard disk is full or the memory is full, you will no longer be able to record anything, so you run the risk of losing your work in progress.

This is why it is essential to always keep enough space in its memory to perform exchanges with RAM.

In general, it is advisable to leave at least 10% of the total capacity available (e.g. 25 GB on a 256 GB SSD).

This is a minimum because macOS sometimes has a lot of free space to download and install “big” updates.

Of course, your Mac’s memory fills up over time based on the applications you install, the documents you create, the photos and videos you accumulate, and so on.

The process is simple, your Mac’s hard drive also stores files that have become useless (applications you never use, obsolete documents, forgotten files in the Trash, etc.).

Worse, in addition to the data you voluntarily store, the system and applications generate a multitude of temporary files (including buffers and caches for web browsers).

Some are supposed to be automatically deleted, but most remain and fill the MAC storage memory.

In short, even if you use your Mac in a “normal” and “prudent” way, it will eventually become heavy and slow, it is inevitable.

That is why it is essential to regularly clean it of all temporary files, before it becomes completely clogged.

Before starting a thorough cleanup, you should determine if storage space is the cause of your Mac’s slowdown.

Luckily, macOS has tools to help you figure it out.

In the storage management window, the left column shows the space occupied by the different categories:

Applications (the software installed on your Mac, the Recycle Bin (all files that have been placed in the Recycle Bin, but not yet deleted).

Creation of music (audio files from the Garage Band application).

Documents (all files spread across the storage space, including downloaded files, but not photos and videos via the Photos application).

iCloud Drive (files stored in the online storage service linked to your Apple account).

Mail (all e-mail, including attachments, received and sent by the MacOS Mail application, but not messages handled by other e-mail applications, which are included in the Documents category).

Messages (messages sent and received through the macOS Messages application, with attached images), Photos (all photos and videos managed by the application to the macOS Photos application).

Podcasts (audio recordings downloaded with the Apple app), TV (videos downloaded with the AppleTV app, purchased from the iTunes Store or through an Apple TV+ subscription).

Likewise, it may also be important to verify these points:

Other users (data related to other user accounts created on your Mac, which you obviously cannot delete instead).

System (all macOS-related items, which are inherently sensitive) and Other (a category containing everything that is not stored elsewhere).

The space taken up by the latter can vary greatly, especially if you use Time Machine, the Mac’s built-in external drive backup feature.

This may involve the use of a sometimes considerable portion of your internal storage space saving files useful for backup.

MacOS takes care of everything automatically with its automatic system and will know how to free up space if it needs to, without losing your data, which is therefore backed up on the external drive.

The first thing to clean on a Mac is the trash can. We forget it all too often, but it contains files that remain on the disk until it is empty.

This is the easiest and fastest way to free up storage space.

You can empty the recycle garbage can in several ways, including automatically.

Right-click on the Trash icon in the Dock folder, and select Empty Trash from the menu that appears.

Left-click the Trash icon in the Dock to display its contents, then click the Empty button in the upper right corner of the window that appears.

In both cases, a confirmation window appears in the center of the screen.

Click on the Empty Trash button to validate.

Another finer method to empty the Trash: go through the storage management window of your Mac (via the Apple menu, see above).

In this window, click on the Trash in the left column.

You can then decide to delete only some of the larger files by selecting them and clicking the Delete button in the lower right corner.

Or simply empty it completely using the Yes button at the top.

The storage space management window allows you to easily make the space on the Mac disk drive.

Open the storage management window as explained above.

Then click on the Documents section in the left column.

In the main area of the window, you will easily find the largest files.

By default, they are sorted in descending order of size. If this is not the case, click on the Size column to return to it.

Click on the other column headers to sort the list by file name, file type or date last opened (Last Accessed). You find a large file that you no longer have

Need? Select it and then click the Delete As button at the bottom right.

Every time a file is downloaded from the Internet, regardless of the browser used, it will be nested by default in the folder named Downloads.

This is useful, but it is often forgotten that it exists and so it gradually fills up until it takes up several gigabytes.

To easily clean it up, click the Downloads tab in the Documents section of your Mac’s Storage Explorer window.

The list will then display all the files in the Mac download folder, which you can sort by size to get rid of the largest ones first.

Feel free to go through the whole list: there may be other files that have been out there for a long time, such as older versions of software installers (files ending in .dmg or .pkg) that you no longer have, but which you can always re-download if necessary. And probably in newer versions.

Not only documents, photos and other videos take up space on a Mac hard drive: applications do too. Especially if some of them are not used…

To delete them, you can use the storage management window again.

But we advise you to check out our convenient Uninstall apps cleanly on Mac, which will show you how to actually remove them completely and save even more space.

Open the storage management window as explained above.

To view all the applications installed on your Mac and see which ones take up the most space, click on the Applications section in the left column.

By default, they appear there in descending order of size. To delete an application, select its name in the

list, and then click the Delete button in the lower right corner.

iCloud Drive is Apple’s online storage service (via the Internet), equivalent to the famous Dropbox.

If you have activated it during the installation phase of your Mac or later, through the System Preferences, iCloud Drive is responsible for synchronizing the contents of two folders on your Mac with the online storage space linked to your Apple account.

Of course, the behavior of iCloud Drive has an impact on your Mac’s storage space.

This service can work in two different ways: either you can store all files and folders that you also entrust to iCloud Drive identically on your Mac.

Likewise, you can run in the so-called “optimized” mode, in which case you let macOS delete the least used files on your Mac to make disk space when needed.

Of course, these files remain safely in your online space, and macOS takes care of retrieving them from the Internet on demand if you double-click on them.

These files are identified by the small cloud icon next to their name: if you see it, it means that the file is no longer on your Mac, but on your computer.


To see how much space iCloud Drive takes up, open your Mac’s Storage Explorer window as explained above, then click on the iCloud Drive section in the left column.

By default, it does not display a list of files stored in this folder that are accessible by the Finder.

To change the behavior of iCloud Drive, click on the Apple menu, then System Preferences.

In the Preferences window, click on the login icon.


Click on the iCloud section in the left column, then click on the options button opposite the iCloud Drive row.

In the window that opens, check or uncheck the Folders box.

Desktop and Documents to enable or disable synchronization of these folders.

Then click on “Done”.

In the above window, click the Optimize Mac storage checkbox to allow macOS to securely delete Mac files in the cloud.

Uncheck this box if you prefer to ensure that all files remain both online and on the Mac, which will take up more space.

In addition to the data you voluntarily store on your Mac, the system and some applications generate files that you do not have direct access to, but which can take up a significant amount of space.

These are mainly temporary files (also called “buffers” or “caches”), created by web browsers and others, which can accumulate over time.

It is also these files that sometimes trigger the Other category, which is displayed in the storage information window for your Mac.

There are many specialized applications that offer cleaning tools to get rid of them. Some of them, such as Clean My Mac, Safe Mac Washing Machine,…

X9 or CCleaner are not free, but they are also available in trial version to get an idea.

But one of the most effective in this field is totally free: OnyX, from Titanium Software.

Let’s face it, this application should be used with all necessary tongs.

First of all, you must install the version intended for your macOS version without fail.

Next, you need to be patient: most of the operations you will ask OnyX to perform take several minutes, even tens of minutes on an older machine with a classic hard disk instead of an SSD.

So be patient and do not interrupt ongoing operations.

First, check the version of macOS installed on your Mac.

To do this, pull down the Apple menu and click About This Mac.

The version of the system installed on your Mac is displayed in plain text in the information window.

Using your web browser, download the version of OnyX and try to make sure it is the version for your macOS.

After downloading, install OnyX. You will need to enter your account password to grant the application permissions.

Once OnyX is launched, click on the Maintenance tab at the top.

Then check the checkboxes for the cleaning and optimization functions:

File system structure and Delete local snapshots typed over time in the section Testing.

System, Applications, Internet and History Messages and Reports in the Cleanup section, and possibly Trash and Trash in the miscellaneous options section.

For your information, System refers to system files that your Mac does not need and that you can safely delete.

Buffer Applications refers to the applications you have used, such as those related to audio processing and Java.

Internet to the numerous data related to your visits (browser caches, histories, forms, cookies).

History messages and reports to diagnostic data

generated by both applications and the system (not useful in everyday life).

To avoid deleting too many things, including the usernames and passwords you use to access online services, click the Options… button to the right of this section to fine-tune the cleanup.

In the one that appears, you can check everything except the Form Information box.

Otherwise, you will have to re-enter your user name and password, which will no longer be stored… Click on OK.

when finished to return to the main window.

When all the cleaning options are configured, click on the bottom right of the race.

A window indicates that the Mac will restart automatically at the end of the operation.

Then all you have to do is compare the space occupied on your Mac before and after.

After cleaning, if you want to optimize your Mac, click the Utilities tab.

In the File System subsection, you can run a global check of the structure of files and folders stored on the Mac.

This is a time-consuming process – again, you’ll have to wait – but it can detect anomalies and

make your Mac more responsive by fixing them.

OnyX also allows you to change hidden macOS settings via the Settings tab, which is full of settings that would be too long to detail here.

Note that you can, for example, change the default name of the screenshots and avoid including window shadows.

Modify some items that appear in the Finder menus, change the behavior of the Dock, enable or disable the Mac startup sound, reactivate the font smoothing feature that has disappeared from Big Sur, and so on and so forth.

In summary, a great set of tools for the

“tuning”, which will delight those who like to have a “customized” Mac.

OnyX alerts you when certain actions should be handled more carefully than others.

That said, always remember to back up your Mac before embarking on any powerful optimization operation.

In case of an accident, at least you will recover your Mac as it was before: even if it is slow, it will be more useful than if it doesn’t work.

Other Options:

You can also get digital manuals on this subject at Amazon. Each of these manuals can be found in great online offers.

In addition, in the App Store apps you can get these apps for free.

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