The essential guide to cleaning & speeding up your Mac

 Sandro Villinger, 20 March 2018

Macs don’t ever slow down, don’t ever crash, and sure as rain don’t ever run out of space. Right? Wrong.

Unfortunately, Macs might be the sports cars of the IT business, but just like any car, they need proper maintenance to keep running. In this guide we’ll walk you through the essentials — and even some great secrets — to clean up invisible clutter and tune up your MacBook, iMac, or Mac Pro beyond its limits. 

If your Mac is running slow, you might be looking at a lot of different symptoms such as applications taking ages to start or your browser feeling sluggish despite a fast internet connection. Other times you’ll hear the fans ramping up to levels that would put your vacuum to shame. Worst case scenario, your Mac slows down to a crawl until it freezes.

Why is my Mac running so slow?

A slow Mac can be caused by a lot of different factors, including:

In this guide, we’ll go through the most common causes of slowdowns and help you fix them.

Technical background

The internals of a Mac are almost identical to modern PCs. And macOS is bound by the same rules that plague Windows: as you install more and more programs or reach the limits of your disk space, you’ll experience drastic slowdowns in your day to day work. In our tests, that slowdown can be even worse than on equivalent Windows machines.

Let’s have a look a look at what happens when we fill up the disk space on a 2016 15” MacBook Pro with touch bar, 2.6 GHz Core i7, 16 GB RAM, AMD Radeon 460 PRO, and a 512 GB SSD.  

Startup time of a Mac with full disk space (lower is better)
50 GB available disk space: 11 seconds
250 MB available disk space: 39 seconds

Launching Outlook 2016 for Mac (lower is better)
50 GB available disk space: 3 seconds
250 MB available disk space: 8 seconds

Converting a 200 MB 4K video file (lower is better)
50 GB available disk space: 9 seconds
250 MB available disk space: 32 seconds

These results partially show how even the fastest machines are bogged down by low disk space. Every click came with a delay or an error message, which is mostly caused by the virtual memory system of macOS and not enough space in the temporary caches of your applications. Without that space, applications won’t work as expected, resulting in either crashes or slowdowns.

But it’s also the additional app or program that runs automatically at startup or in the background that slows things down quite a bit, even on modern Macs.

At any rate, if you’re reading this, chances are your Mac is in some form of peril. This is why we’re here. We’ll start by showing you the essential tips to cleaning up a Mac before we delve into some tips to improve speeds and battery life.

The Basics

Get those updates going

To optimize and boost your Mac’s performance, first things first: make sure that your macOS is up to date. Apple always finds a way to improve performance or to get rid of bottlenecks that plague your Mac. Either way, unless your Mac is hopelessly outdated or not supported anymore, the latest macOS updates tend to make things run smoother.

To check for updates, open the Mac App Store and click on the Updates category. Install updates for everything that you see listed there.


Remove applications you’ve long abandoned

Just like PCs, the more programs you install, the more you have going on in the background. Free yourself from this clutter by going through your list of applications and carefully deciding which ones you need and which ones you don’t.

You’ll find the list by going to your desktop menu bar, clicking on Go and selecting Applications.


To uninstall an app you can either drag it to the Recycle Bin or right-click and select Move to Trash. This isn’t perfect, though. Uninstalling apps typically leaves behind some cache files, settings, or other temporary data which (spoiler alert) you will learn to remove with one of our own tools.

Get some basic disk maintenance going

Every so often your disk needs a regular health check to prevent errors and data loss. If some problems are found, it can instantly fix them. But if it can’t, it is usually a sign that your hard disk is about to give up, which means one thing: backup time!

To perform a scan, click on Go in the menu bar and head over to Utilities. From here, click on Disk Utility. Select your main hard disk and click on First Aid.


Next, you’ll see a summary of issues found. If you see an error, it’s time to launch a repair:


In the example, macOS found corruptions in the file system, which can only be repaired by going into your Mac’s recovery environment and launching First Aid(holding down the Command key + R gets you into recovery mode).

Reset SMC & PRAM once in awhile

SMC? PRAM? Sounds scary, but it isn’t.

All Macs have a System Management Controller (SMC). This is a chip inside your Mac that controls its ports, fans, power button, Wi-Fi, power management, and many other physical parts. By using your Mac and lots of accessories, the SMC could become corrupt.

Meanwhile, the Parameter Random Access Memory (or PRAM) is a small memory chip which contains basic system settings like trackpad sensitivity, date and time, volume, and keyboard backlight. Over time and through many updates, this too can become buggy.

If you’re experiencing strange problems like blank displays, Wi-Fi issues, fans running at full speed, random shutdowns, slowdowns, USB ports not working, and more (the list goes on), then resetting the SMC and PRAM might work well.

How to reset the SMC

Reset SMC: For MacBooks with a non-removable battery
To reset the SMC, you have to shutdown your Mac completely. Now, while it’s off, hold down SHIFT + CONTROL + OPTION on your keyboards (left side), and press the power button. Hold all those keys for 10 seconds (and try not to get a cramp). Release the keys and power on your Mac normally.



Reset SMC: For a MacBook with a removable battery
Shutdown your MacBook, remove the power cord, remove the battery, and hold the power button for at leaast 5 seconds. Then put the battery back, plug your MacBook in, and turn it on. That’s it.

Reset SMC: For your Mac desktop
Shutdown your Mac, remove the power cord, wait for 15-20 seconds, plug it back in, and turn it on. Couldn’t be easier.

How to reset the PRAM 

To reset the PRAM (this applies to all machines), you need to shutdown your Mac and press the power button. Immediately push COMMAND, OPTION, P and R at the same time. Keep these keys pushed until your Mac reboots — then release.

That should fix many strange Mac issues that you couldn’t solve otherwise.

Cleaning up your Mac, top to bottom

Check what’s really occupying your disk

Say you forget all the files you have, and you want to know what’s occupying so many gigabytes of disk space. There’s an easy way to find out. First, click the Mac icon in the top left corner, then click Storage. Wait a bit until the calculation is complete:


In the example, you can see that a massive Photos library, possibly residing in a subfolder that’s been buried, amounts to almost 17 GB. For a more detailed glimpse, go to Manage.

Start with the Recommendations category at the top of the list: Following the advice will help remove iTunes movies and TV shows you’ve watched, empty the trash and sort through files (which takes you to the file manager mentioned above).

Under the first category, Applications, you can see which apps take up the most space (and delete them right away if you don’t need them).


Under Documents, you have an easy view of large files, downloads, and access to  the file browser. The latter shows huge folders and allows you to see what’s hidden where.


Next, you can turn your attention to other files like iBooks to delete books you’ve read or audio books you’ve already listened to.

Oftentimes, iTunes will store massive iPhone backups, which you can delete as they usually take up many gigabytes of space. (But only delete older ones that you’re sure you won’t need!) You’ll find those under iOS files.

Another biggie might be Messages: if you use the app iMessage on your Mac, it stores ALL movies, photos, and even files like PDFs in a hidden folder. In the case below, it grew to 1.27 GB. (And, for real, it took less than 4 weeks!)


If you (like us) are not the most talented musicians, you might want to delete the GarageBand sound library under Music Creation, which can free up 2.3 GB on macOS High Sierra. Last but not least, turn on the iCloud Photo Library which moves your local library to the cloud, saving you another few GBs. Note, though, this only makes real sense for iCloud users.

How to clean cache files on MacOS

You can also do some basic cleaning of application caches, which are files that apps keep around long after they need them. To do this, open Finder and click on Go To Folder in the Go menu. Enter the following: ~/Library/Caches

Now, open up each and every individual folder and empty the content. Do not delete the folders themselves, as this might result in some issues with your apps.


Unfortunately, you have to do this on a regular basis, and this cache is only one area where macOS and your apps store their temporary files. It’s why we built Avast Cleanup Pro which scans your Mac top-to-bottom for these files and gets rid of them automatically for you — across your entire hard disk. Our cleanup application gets rid of all the junk you don’t need on your MacBook, Mac, or iMac.


 Examples of things we clean up:

  • Apple help: Temporary caches from Apple’s help files.
  • Safari user cache: Temporary browsing files from Safari.
  • Location services: Temporarily stored files from the location services of macOS.
  • Spotify: Leftover data from the Spotify app.
  • Photos: Wasteful cache files from the Photos app.
  • Log files: These files are generated on a regular basis by macOS and installed programs when you’re encountering a problem or just to protocol normal operation. For example, macOS logs every crash under /Library/Logs/DiagnosticsReport, which can grow to hundreds of megabytes in size. But when programs crash, the relevant information will be stored in a folder called CrashReporter. These files contain information about your PC, some user information, and, in some cases, a huge amount of data on the crash itself. Unless you’re a developer, this information is useless and can be safely deleted using Avast Cleanup Pro.
  • Trash: The recycle bin of macOS. As many users forget to delete this, our cleanup tool provides a safe way to clear it out in one go.
  • Downloads: As the default location for users’ downloads, this can include long-forgotten and sometimes massive amounts of data the user doesn’t need anymore.
  • Development junk: Programmers will appreciate the fact that Avast Cleanup Pro removes temporary leftover files, such as XCode temp files.
  • External hard disk junk: MacOS also stores temporary files on external disks once they’re connected. We remove these so none of your USB drives are being cluttered with files you don’t need.
  • Duplicate files: Every once in a while, users or programs accidentally copy (duplicate) files. This can happen if you download multiple copies of the same file, duplicate photos or videos to edit and forget about them, or accidentally backup files more than once, just to name a few scenarios. You will be surprised by how many duplicates can be found on even the tidiest Mac. 

    Copyright © 2004 -2019 Intelligent web technology. All rights reserved.