How to speed up a slow Mac

It might sound obvious but the best place to start is to close down any unused programs. If you've got too many programs running at once your Mac may devote memory and CPU space to them instead of to the apps you want.

Right-click on programs in the Dock and choose Quit, or press Command-Tab to bring up the App Switcher and press Command-Q to quit unused programs.

Pro tip! Software like iStat Pro can be used to monitor your app performance in real-time.

See also: How to uninstall a software application in Mac OS X

If you're worried about performance you should make sure you can see which apps are running. Open System Preferences and click Dock. Ensure there is a tick next to 'Show indicator lights for open applications'.

Read next: Mac System Preferences Guide and Best Mac buying guide 2016

If you want to see what apps are using up your system resources, open the Activity Monitor in the Utilities folder.

Activity Monitor shows all the processes on your Mac (some of which you can't, or shouldn't, close) so click on View and Windowed Processes. Now click on the CPU button and the "%CPU" column to list all programs by the amount of CPU they are using. You can also use this to see what Memory, Disk and Network different processes are using.

A feature added in Mavericks was Energy, which enables you to see which apps and processes are using up the most amount of energy from your battery.

Read: Apple Support - Using Activity Monitor

Open System Preferences and check in the row at the bottom. This is where custom items are added to your System Preferences and if you're not using them then they are taking up your CPU. Right-click on an item and choose Remove From Preference Pane.

Open System Preferences and click Users & Groups. Now click on the Login Items tab to view which programs and services are launched when you first power up (or log in) to your Mac. Highlight an item in the list that you don't want and click on the Delete from Login Items (-) button at the bottom of the list.

It's usually best to keep some space free on your Mac (we usually aim for around 10 per cent). Start by emptying the Trash (right-click on Trash in the dock and choose Empty Trash).

If you need to free up more space then check through your User folder for items to get rid of (Movies and Pictures are often likely culprits). You should also empty the Downloads folder of any items you're unlikely to need.

See also: How to speed up a Mac hard disk

It's often a good idea to start removing apps that you really don't use. You can just drag and drop apps into the Trash, but we advise you to invest in a program called App Zapper that can show you how much hard drive space apps are taking up and when you last used them, and can delete apps and all associated files.

You should also remove any widgets that you don't use from the Dashboard. Click the Remove (-) icon in the bottom-left and tap on the Remove ('X') icons on any widgets that you don't regularly use.

Unresponsive apps? Here's how to ctrl-alt-delete on a Mac, aka Force Quit on a Mac

Make sure you perform a software update for Mac OS X and macOS Sierra and all the apps installed in Mac. Click on the Apple icon in the Menu bar and choose Software Update (or open Software Update in the App Store).

If you have apps purchased outside of the App Store they will need to be updated separately. You'll usually find Check for Software Update from the program name in the Menu bar.

AppFresh is an app that can help keep track of all your software and checks constantly to see if updates are available. Some apps can also self update by integrating with AppFresh.

You should also make sure that Mac OS X and macOS Sierra keeps itself up to date. Click on System Preferences > App Store and ensure that Automatically Check For Updates is ticked. You can also tick Install App Updates which will automatically ensure that apps are updated.

Safari sometimes gets clogged up with data. Cleaning this out will help speed up Safari in Mac OS X and macOS Sierra. Open Safari and choose Safari > Reset Safari and check Remove all Website Data. (Leave the other options unticked.) Now click on Reset. This can help speed up sluggish web browsing.

Open Disk Utility and choose your main hard drive from the sidebar (in most Macs there will only be one.) Now click on First Aid and Repair Permissions. This will ensure that all the files on your Mac have the correct permissions, which will help keep things ticking along.

As of El Capitan (and macOS Sierra), you can no longer repair permissions in Disk Utility. It's gone because the new System Integrity Protection (SIP) in El Capitan and macOS Sierra prevents permissions on files being modified which, according to Apple at least, means there should be no need to repair permissions.

Read next: How to defrag your Mac

Most Macs can run OS X and macOS Sierra without any trouble. But some people prefer to have keep the Dock static to prevent slowdown. Click System Preferences > Dock and untick the following check boxes:

• Magnification
• Animate opening applications
• Automatically hide and show the dock
• Turn off accessibility

Now click on 'Minimize windows using' and change Genie Effect to Scale Effect.

Historically, upgrading RAM has been the goto solution for improving your Mac's performance. Before you go ahead and spend money, however, it's worth trying to figure out how much of a difference it will really make, if any. The easiest way to do this is to fire up Activity Monitor (it's in Applications/Utilities), click on the Memory tab and keep an eye on the memory pressure gauge at the bottom of the window. If it's permanently green, you're probably not going to see a huge difference by upgrading. If it turns red regularly, it's worth the expenditure.

How much RAM you add and how you add it is dependent on your Mac. But as a rule of thumb, the effort of performing the installation compare with the marginal cost of bigger RAM modules means that it's worth maxing out your Mac's RAM in one go.

That will often mean removing the existing modules and replacing them. It's a good idea, though not essential, to buy all the RAM you fit at the same time from the same manufacturer. If you decide just to fill empty slots, the same applies. And you should pair RAM modules of the same capacity, if possible.

Read more: How to install extra RAM in a Mac

Every file on your desktop is a window with an image in it - either an icon or a preview of the file. Each of those windows and their contents is stored in RAM so that when you switch to the Desktop or use QuickLook, your Mac can show you what's in the window. In other words, the more files you have on your desktop, the more data is stored in RAM. That could result in your Mac running more slowly, especially if your Mac's memory is already under pressure.

Organise files properly in the appropriate user folder - Documents, Pictures, Movies etc - and you may see an improvement in the speed of your Mac.

Macs are so stable and so power-efficient when they sleep that most of us don't bother shutting them down regularly, especially if they are notebooks. That means caches don't get flushed and applications that hog RAM don't let it go.

Restarting your Mac clears the caches and shuts down applications. The result is a Mac that's refreshed and should perform better.

Spotlight, particularly in recent versions of OS X and macOS Sierra, is a terrific tool. But if you use multiple drives, particular on older Macs, it can take Spotlight to index and re-index the filesystem. That in turn will slow down your Mac.

The answer is to manage Spotlight to limit the files it indexes. This is done in the Spotlight pane in System Preferences. Once you've opened the pane, click on the Privacy tab. You can now drag any folders or volumes that you don't need to search on to the window. That will stop Spotlight indexing the folder or volume and thus reduce the number of files it needs to index, meaning it spends less time indexing and should improve performance on your Mac.

Most of the current crop of Macs come fitted with SSD storage in place of a hard drive. SSD is smaller, uses less power, and significantly faster than a hard drive. It's also, however, more expensive per GB.

To provide inexpensive high capacity storage alongside the speed benefits of SSD, Apple came up with the Fusion drive - an SSD and a hard drive that your Mac sees as one volume, but which keeps the system and applications on the fast SSD while putting documents, photos, music and video on the hard drive.

You can make your own fusion drive if you have a spare hard drive bay in your Mac, or if you have an optical drive you don't need. The instructions on how to do it are here.

By default, opening a new Finder window takes you to the All My Files view, which displays every file on your Mac. If you have an older Mac and lots of files - especially if they're image files or videos and so display a preview of their contents - this could slow down your Mac.

Change the folder that's displayed when you open a new Finder window by going to Finder Preferences, clicking the General tab and choosing a different folder from the drop down menu.

File Vault allows you to encrypt every file you store on your Mac to keep it safe from prying eyes. It also uses lots of processor cycles, however, to encrypt and de-crypt those files. If you use it currently, switch it off and see if you notice a difference in performance.

Click on the Security & Privacy tab in System Preferences, then on the File Vault tab. Click the padlock, type in an admin password, and click Turn off File Vault.

If all else fails, and you've tried everything we've suggested to speed up your Mac without success, there is one more option: a clean re-installation of the OS. It's not a job to be undertaken lightly - you'll need to delete your entire boot drive. But, it will clear all the files that have collected in the system Library and the user Libraries over the years and which may be causing the Mac to run slowly.

I gave new life to a 2009 iMac which had been running Lion, and was grinding to a halt, by doing a clean install of El Capitan or macOS Sierra. It now feels like a new machine.

Remember to make at least one, preferably two, complete back ups of your bit drive before you start so you can copy documents, images, music and anything else you need back once you've installed the new OS.