I know, OS X 10.10 memory management knows what it does, it is good, you shouldn't question it. But this, I do not understand. I have 16 GB of RAM, 6 GB used, plus 2.5 GB app-cache, 1 GB file-cache and 1.5 GB reserved is a total of 11 GB used memory. But for some reason, I have 1 GB of compressed memory and about .5 GB of used swap. Whenever the system starts to use swap, it get's noticeably laggy. Because of this, I have to reboot about once a day.

What do I miss here? Why swap? Why compressed memory? Why lag?

Maybe there are some clevererer people than me around here. Any answer as to WHY is greatly appreciated.

Here is a screenshot of the memory tab of Activity Monitor:

Activity Monitor

  • Is OS X using swap, or applications that are running? Commented Mar 6, 2015 at 15:51
  • We would need to know much more. OS X itself doesn't use 16GB of RAM, so there are other applications involved that use the memory. Commented Mar 6, 2015 at 15:55
  • I'll take a guess here, you're using Yosemite? Commented Mar 6, 2015 at 15:57
  • Hi, yes I'm using Yosemite. i.imgur.com/0lCm4xX.png
    – senthor
    Commented Mar 6, 2015 at 16:07
  • 1
    That screen shot shows you to be just fine, in great shape, the memory pressure is extremely low. What is slowing down is not showing up there. memory management is usually dealing with system requirement and applications you are using. It will compress some if they have been used (recently) but not at the moment. We need a screen shot of the situation just before you want to restart the system because it is "sluggish"- Träge.
    – Ruskes
    Commented Mar 6, 2015 at 16:43

1 Answer 1


The values in your image look fine. Since the system is lagging, why not measure things over time:

vm_stat 60

You can let that run in a terminal to get an aggregate feel for when swapping happens and at what rate. It's highly likely that some other thing is the bottleneck like CPU or storage, but without seeing things change over time, it's hard to say what's causing the lag. I've never seen a system lag due to RAM without the memory pressure being yellow or worse, but that doesn't mean it's impossible to have.

That coupled with the fact that your system still has 10 GB of free RAM makes it even less likely it's contention for memory/swap causing slowness. Feel free to ping me if I miss an edit to the question with more data to go on.

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