Mac Activity Monitor CPU Usage

How to Use Activity Monitor on Your Mac?

Your Mac’s in-built Activity Monitor is a pretty neat diagnostic tool. With just a quick view, you can easily find out why our Mac is struggling and if it is struggling, especially with slow speeds.

Here’s a quick look at what you can see in your activity monitor and how you can interpret what you see.

First, this is how you open Activity Monitor on your Mac. Go to Applications -> Utilities -> Activity Monitor. You can alternatively find a quick shortcut to Activity Monitor through a Spotlight search.

Your Mac’s Activity Monitor and what it shows you

5 Categories : 1 CPU, 2 Memory, 3 Energy, 4 Disk, 5 Network

5 Elements of Mac's Activity Monitor



Mac Activity Monitor CPU UsageThe CPU column is the most important column in your Mac’s Activity Monitor. Since what you see can be sorted in real-time, the first thing you must do is click on the little tab that says % CPU, at the top of the CPU column. What this will do is show you what app is using what % of your CPU.

Generally, no app will use more than 4%-5% of your Mac’s CPU resources. If it does, it means that something is wrong and that you must probably shut down the app and restart it, to see if it will run smoothly the second time around. In some cases, an app might always use too much CPU resource. For example, Adobe Photoshop is a pretty heavy program that requires a lot of CPU power. If this app continuously uses 5%+ CPU resources, you just have to live with the slowness that it brings to your Mac. Or, you can consider hardware upgrades like RAM or SSD upgrade.

At the bottom of the Activity Monitor, when CPU is selected, you will see a summary of how much CPU power is used by system apps and how much is being used by User or the apps that you run. Again, system consumption should be less than 3% almost always. If your system consumption is always hovering over 5%, it means that your OS X or Mac OS is corrupted and that it needs a fix.

2 Memory

Mac Activity Monitor RAM usageSelecting the memory column will show you how much RAM your Mac is using and for what. A fairly heavy app like iTunes will typically use about 90 MB of memory. A Safari tab will use about 32 MB of memory.

The key here will be to look at the memory pressure chart at the bottom of the Activity Monitor (When memory is selected). If you see red spikes once in a while, it’s OK. When you start up a program like iTunes, your Mac is going to be temporarily busy until it opens up the program, showing a red spike in memory usage. But, it should settle down. If you continuously see red spikes and also see an app consistently consuming more than 100 MB of memory, it means that the app is not functioning efficiently, for whatever reason. You must investigate it.

While here, make sure that your physical memory shows the correct amount of RAM on your Mac. If you installed new RAM but installed it incorrectly, it won’t add up in this number and you can diagnose the problem and install the RAM properly.

3 Energy

Mac Activity Monitor Energy UsageThis is the tab you want to explore if you want to investigate why your Mac loses a lot of battery power and loses it quickly. The populated list will tell you what app is consuming how much power from your Mac. Some apps are very power hungry and will drain your battery a lot quicker than some other apps.

You will also be able to see what apps can prevent your Mac from sleeping, just because they are open and running. A program like iTunes has a memory impact of almost 9.9 whereas another program like Numbers or Sheets hardly causes any sort of energy impact.

At the bottom, you will see some very vital statistics about how much charge remains and how much longer your battery is estimated to last. You will also see a neat little column that tells you if a high performance graphics card is being used. Most Macs have both a high-performance graphics card and an integrated, more basic graphics card. For simple programs like Mail, Numbers etc, the “Integrated” card will be used. But, when you play games or use a video player, you will see “High Perf.” displayed as the choice of graphics card. ¬†Again, this might come in handy when you are trying to identify rogue apps that might be cranking up your high-performance video card all the time, thereby killing your battery in double time.

4 Disk

Mac Activity Monitor Disk UsageDepending on what you do on your Mac, you are going to see either a lot of “Bytes Written” or “Bytes Read” or maybe both when you look at this column. It shows how actively your Mac’s hard disk is being read or written on. Look at the graph at the bottom. Blue peaks show that data is being read while red peaks show that data is being written. If you see a lot of spikes in blue, red, or both together, you will heavily benefit from replacing your HDD with a SSD.

Even if you have to stick with a HDD, you can improve these speeds by freeing up disk space on your HDD.

5 Network

Mac Activity Monitor Network UsageThis is the tab you want to investigate when your Mac is mysteriously consuming bandwidth, without you really knowing what app is using the internet so much. Nowadays, all apps use the Internet. But, the chart that shows blue packets received and red packets sent should be spikes that fall and rise, with periods of rest in between. If you see a lot of red or blue, it means some app is very actively using the internet, burning up your bandwidth.

So, keep an eye on this tab when you just can’t figure out what app is eating into your monthly internet data plan.

Use your Mac’s Activity Monitor anytime you face performance issues. Using it when the performance issue actually occurs is the best time, as it will help you identify what exactly is causing your Mac to act funny. On the flip side, Activity Monitor itself is a bit of a heavy app when it comes to CPU or Memory usage. So, don’t keep it running always and definitely don’t set it to run as a login or startup item. Use it only on a need-to-use basis.

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