Is there any recommended way of checking for this?

There is another thread:

How do I find how much disk space a program is occupying?

I ask this question because I was under the impression that disk space is not the same as RAM. My computer is running slow and I would like to get to the cause, and the first thing I want to tackle is finding out which programs are taking up the most RAM.


  • Since your first question was answered, who is using what, lets talk about slow computer :) Is it slow on Internet, or slow without it. Look in the activity monitor the CPU tab, and see who is most active, then report here. – Ruskes Jul 8 '14 at 9:13
  • Check out Memory Clean - I use it a lot its really useful for mavericks. – Dean Jul 8 '14 at 10:10

If you go to the Utility folder on your Mac, open the Activity Moniitor.

Then go to the Memory tab.

There you will see who is using how much.

There is also a Disk Tab, where you can also see who is using how much on active basis (when programs are running). You wont see the passive usage (how much information is stored) in that window.

In this example the application Firefox

Using Memory:


Using Disk space:


How much space is a Application occupying on the disk, is answered by looking in your Finder -Applications then under the - Size coulomb.

Again in my example, the Firefox occupies 147 MB of permanent disk space, which is not the same as the information above which was for the active situation.

Back to your original problem- slow computer:

In the Activity Monitor look now in the CPU tab to see who is most active there.

  • Hi, Buscar. I think mine shows a System Memory tab as opposed to Memory tab. When looking at how much RAM a program takes up, do we look at Memory column, in mine it's called Real Mem? I have a column that is CPU%, is this a percentage representation of Memory column? – jason adams Jul 8 '14 at 10:52
  • @jasonadams System memory is the same as Memory (RAM). Yes use the Real Mem, as guide how much is used of it.The CPU% is not memory! The CPU is the brain, doing all the work, and the % shows how much work it does on specific application. The CPU does not saves anything. – Ruskes Jul 8 '14 at 11:02
  • so is CPU % in any way correlated to Memory? I would think that the more Memory (RAM) a program uses up, the more CPU % would go up? – jason adams Jul 8 '14 at 14:53
  • No, the CPU percentage has no direct correlation with the memory usage - the CPU % tells you how much work the application is doing - and the memory usage tells you how much RAM its using to store everything it needs to do it's work – ThorinII Jul 8 '14 at 21:55
  • In some ways they are correlated, the CPU gives the memory (RAM) work to do, but sometimes the CPU just has to figure it out by it self (calculate). So not directly correlated but most of the time you see increase in CPU% and RAM usage. – Ruskes Jul 8 '14 at 21:58

Search on Spotlight for activity monitor - switch to the Memory Tab.

Then you should see something like that:

enter image description here

There you will see how many memory each Process is using at the moment.

I hope this answers you question.

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