There are many ways to optimize an Apple Mac so that it starts up faster and runs more smoothly, but here I am going to use a utility called MacCleaner Pro. It’s a utility with many uses.
Whether you have an old Apple Mac desktop or a new Apple MacBook Air M1, it is useful to optimize the startup and overall speed, but these tips are more beneficial for older computers than new ones.
Old Macs have less powerful hardware and limited resources like memory. They also tend to have more software as it builds up over the years. Too much software and too little memory are the biggest causes of a slow computer. However, there are things you can do to boost the performance.
MacCleaner Pro is actually a collection of several utilities, but here I just use the main program. It is a useful tool to have on your Mac and it performs several tasks. Optimizing the startup and making the Mac run smoother is just one feature. See more at the Nektony website. (Affiliate link.)
Speed up the Mac the easy way
Run MacCleaner Pro and wait until it has finished scanning the system. The first time it runs, you must open System Preferences > Security & Privacy > Privacy > Full Disk Access and add the app. The Mac annoyingly requires permissions for every little thing these days, so expect a lot of requests, but thankfully you only have to do it once.

When the scan is complete, select Speed up Mac in the sidebar. On the right are four modules: Free up RAM, Disable startup apps, Reindex Spotlight and Reindex Mail. You can simply tick these four items and click the Speed Up button in the bottom right corner.
Switch to expert mode

I prefer not to use the easy mode and instead, I enable Expert mode with the switch in the top right corner of the app window. This increases the number of optimization items to seven and it provides more control over what will happen when the Mac is optimized.
Free up RAM
Click the Free up RAM option to see how much memory is being used on the Mac as a percentage and in gigabytes. If you want to increase the amount of free memory, this option can be selected and the Speed Up button clicked.

There are benefits and drawbacks. The benefit is that more memory is made available for the next app you run and so it will run better and smoother. However, currently running apps and data are pushed to the disk, which makes switching to them slower if you need them again.
It can useful at times to use this feature to free up memory, but another option is Quit heavy consumers. Click this item and it lists the apps currently running and using the most memory. You can easily see the worst offenders and quit them to free up memory for your next app.
You can see in the screenshot that I have 1.24 GB of heavy offenders. The main one is a browser with about 10 tabs open. I could close it to free up RAM rather than use the Free up RAM option.
Disable startup programs
Some apps automatically start when the Mac is started. Some may be essential, such as with security software, which needs to be running all the time, but often non-essential items load on startup and run in the background. They add to the time it takes to get to the Mac desktop and for it to be ready for work, and they run in the background and use memory.
Click Disable startup items and apps and other items are listed. Most of these do not appear in System Preferences > Users & Groups > Login Items and mostly what MacCleaner Pro lists are hidden items, things you don’t see that load and run in the background and slow the Mac down.

You can simply turn off the switches next to items or tick the checkboxes next to ones you do not want to load on startup and click the Speed Up button to disable them. (They can be enabled again.)
Expert users can Ctrl+click items to access a menu of useful actions. Show in Finder for example, opens a Finder window to show the folder where the startup item is stored. This lets you investigate it and, if you prefer, to manually delete the item.
I found startup items for software I no longer had installed. Who knows what problems that might cause? At the very least, the Mac will waste time on startup looking for an item that no longer exists.
Take care not to disable or delete anything important. Basically, if you don’t know what something does, leave it alone. Being able to see what starts with the Mac enables you to investigate them. For example, search for the filenames on Google, Bing or DuckDuckGo and see if they are needed or not.
Reindex Spotlight and Mail
It is rare, but occasionally something goes wrong with Spotlight and Mail. Problems are sometimes obvious and Spotlight cannot find files, folders or apps you know are on the disk. It may also run very slowly or background processes related to it have high CPU usage. Mail can also have similar problems with emails, and it cannot show them or find them, it has constant disk activity or high CPU usage.

Reindexing Spotlight and Mail rebuilds the databases used by these apps. If you do not have a problem, do not reindex them because it takes the Mac time and effort to recreate them, which is pointless if there is nothing wrong. If you do have weird problems with Spotlight or Mail, reindexing can solve them and prevent them using high CPU and RAM in the background.
It may be beneficial to reindex Spotlight and Mail once a year on a heavily used Mac just to have a clear out and refresh. Annually can help boost performance, doing it daily will ruin it.
Browser extensions and plugins
Web browsers can use a lot of memory and processing power and this often occurs when many tabs are open. Try to keep them to a minimum. Another cause of high RAM and CPU usage is plugins and extensions.
Select Remove Internet plugins and Disable browser extensions modules to see what is installed in Safari and other browsers like Chrome. It lists everything and some items are essential built-in features that cannot be removed. Just focus on the items that can be removed.
You can see how much memory each extension or plugin is using and choose whether to keep it or remove it. Performance will improve if you can remove unnecessary extensions and plugins.
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