Making The Most of Activity Monitor

Many Mac users likely haven’t even opened this application before, and those that have were probably scared off by all the numbers and confusing words. I certainly was. But if you understand how it works and what it can be used for, Activity Monitor can be a great way of keeping an eye on what’s going on inside your computer.

This how-to will explain all the ins and outs of Activity Monitor, and how to get the most out of it. It will also give you some tips on how to speed up your computer a bit.

The Interface

Activity Monitor can be located inside the Utilities folder, which is in the Applications folder on your computer. Fire it up, and you should see a window similar to the one here.

The Interface

The Interface

Activity Monitor is a great application to find out if something is really slowing your computer down. To understand your way around Activity Monitor, I’ll let you know what all of the various buttons along the top do:

Quit Process

This button is used for when an application or process is slowing your computer down a lot and you need to kill it. You’ll probably know that you can already force quit stubborn applications for the Force Quit menu found under the ‘Apple’ logo at the top of your screen. However if there is something you can see here that doesn’t usually show up in that menu, you can select it and hit the ‘Quit Process’ button. Make sure you carefully read the dialogue box that pops up, and make sure you never quit something unless you know what it is.


Use this button to find out more information on a selected process or application. This basically gathers all of the information found in the button bar at the bottom and groups it for the selected process. It also contains some other advanced information that only a programmer would probably be able to understand.



Sample Process

Used for finding out specific information on what a process is performing at that time. This is pretty confusing unless you can read code.

Pop Up & Filter

This is actually surprisingly useful. By default, it should be set to “All Processes” which will show you everything. If you change it to “All Processes, Hierarchically”, it will list them so that if one process was created by another, you can see that. This is important because if you quit a parent process, you could also loose other important processes. Have a look through the other options as well for different ways of sorting them. The search Filter is just used for searching for a specific process.

Processes & Applications

All of the important information on processes can be found in the very center of Activity Monitor. You’ll probably notice, depending on what you are sorting by, that the list keeps changing. This is because the processes and their tasks are continually changing while your machine is running even if you aren’t doing anything.

To add or remove columns just right click on the top of them and tick the ones you want. Here’s how to decipher all of the main columns:

Process ID

This is a number assigned to every process and application that runs on your computer, and as a new process is initiated, it is assigned a new number in increased value. This is particularly useful if say you’ve noticed that your computer has suddenly slowed down dramatically. You could sort by Process ID (by clicking it’s header) and the processes at the top should be the ones last opened.

Process Name

This is the name of the process. The names don’t always clearly refer to the actual process though, so don’t mess around with any you aren’t sure about.


This lets you know what percentage of CPU each process is taking up. Usually, this shouldn’t be too high unless you’re performing some intensive tasks. To see what I mean, open iTunes. After it’s finished opening up, the CPU for it should be 0 or close to it. Now start playing some music. You should notice that the CPU jumps up to around 4. Now start the Visualizer. These are very intensive on your computer, and so depending on the one you’ve got running, the CPU should jump massively to somewhere around 90. Maybe thats a good reason not to use visualizers if you are trying to use your computer at the same time.

Real Memory & Virtual Memory

This is the amount of RAM (real memory) and artificial RAM (virtual memory) being used up by each process. Real memory is much faster than virtual memory, but virtual memory is created to perform multi-tasking.


This tells you under which user the process is being run. Useful if you have multiple accounts logged in. Any unusal usernames such as ‘root’ are simply system ones.


This tells you whether the process is Intel or PowerPC

The Buttons Bar

Down the bottom of Activity Monitor you can find useful information on the system as a whole.

The CPU graph shows you how much of the CPU you and the system are using up on the computer. If you want to see a larger graph of this, in the menu bar go: ‘Window’ > ‘CPU History’.

System Memory

System Memory

The System Memory gives you a nice pie chart of how your RAM is being used. It’s fairly self explanatory, but ‘Wired’ memory is “information that can’t be cached to disk, so it must stay in RAM. The amount depends on what applications you are using” according to Apple.

Disk Activity is not so useful for the ordinary user, but Disk Usage is helpful for viewing how much space you’ve used up on any Hard Drive or USB stick for example.

Finally, Network lets you know how much data is coming in and how much is going out. For example, if you are streaming a video you should notice that the Data Received/Sec (in green) will be quite high.

The Dock Icon

One clever feature of Activity Monitor is that you don’t even need to have the window open to get an idea of what’s going on inside your computer.

Just right click on its icon in the dock, and under ‘Dock Icon’ tick one of the different options. My favourite one is ‘Show CPU Usage’, as this gives you information on how much each of the processors on the computer are working.

The Dock Icon

The Dock Icon

You can also get a floating window of the CPU Usage if you’d like it. With Activity Monitor selected, in the menu bar go: ‘Window > Floating CPU Window’.

If you would like to have a quick overview of this information, there are also dashboard widgets such as iStat Pro which may be suitable.

Example Use

One of Activity Monitor’s most useful features is simply the ability to Quit processes. If you’ve been noticing that your computer has been lagging a lot lately, you may wish to take a look inside and see if you can spot anything which might be causing it.

Any processes which show up in red means that they are not responding, and, if they’ve been like that for a while may need to be killed. You may have had the Dock freeze up on you before. If this happens, it may help to restart it by using Activity Monitor. Another example of a good reason to quit a process is if it’s taking up too many of the systems resources.

For example, if you take a look back at the first image of Activity Monitor’s interface, you’ll notice that at the very top of my CPU usage is ‘HP Communications’, consuming 52.4% of my CPU! This could well have been one of the reasons that my computer has been running rather slowly lately, if its constantly using that much. It’s obviously the connection with my HP Printer, and I have no print applications presently open so there is no reason for it to be so high. For this reason, and because I felt confident that I knew what it was, I selected it, and pressed ‘Quit Process’. My printer still prints fine without it running, but that has freed up my resources a lot!

Have a look yourself and see if there’s anything you can do to speed up your computer. Again, make sure you don’t mess with anything you don’t know about though!


As you can see, Activity Monitor can be a little confusing, but with the right understanding it can boost your computers performance and help you work out what’s causing problems, and which applications and processes have the most impact on your system. It certainly can make a difference, as I’ve found after quitting the HP Communications process!

Let us know any tips for using Activity Monitor that you’ve found useful, or how you use it on your Mac.