I thought Mavericks was suppose to utilize RAM memory better, thus run smoother.

Running ML on Mac mini 2012, with 16GB RAM...always running smoothly even with over a dozen apps running.

Now, after installing Mavericks, my Mac is SLOW, eating up RAM like crazy! Looking over usage, of the 16GB of installed memory...on average it uses 10-14 GB RAM when barely running a few apps!!!

There is this kernel_task that is always running with over 1GB of RAM and most apps are not taking that much RAM, so what is using up all my RAM?! File cache? It shows very high in that new description, with about 1/3 of my total RAM

  • Can you provide a dump of activity monitor listed by RAM? Also, is Mavericks writing to page? It shouldn't. If it is, there's a big problem (since you have 16GB RAM).
    – CHM
    Oct 23, 2013 at 5:24
  • I had the same last night. It was using all 16gb of my ram on my imac - now it seems to have stabilised. As Erik mentioned - it may have been due to indexing. I was looking at all processes and nothing was really eating up the ram program wise.
    – user60153
    Oct 23, 2013 at 10:55
  • Mavericks has a great info panel in Activity Monitor. Does your Memory Used exceed your Physical Memory? If so, you might have a problem. If not, you don't. Oct 23, 2013 at 18:38
  • I've noticed the same thing on my 2 mac (iMac and MacBook Pro). Usually, with a lot of apps running, i used 6 Go on 8 Go available. Now with Maverick, i have 8 Go used. Oct 28, 2013 at 23:19

7 Answers 7


Who said that this memory use is bad in any way? At the very least, the OS will be using the memory so that it can spin down your hard drive at the first opportunity. Hard drive access is energetically expensive. RAM is already powered up, so letting it sit idle is truly wasteful.

The question is a yet another post in the style of "oh no my ram is all used up, bad [insert your bogeyman here]". Let's get it out of the way: RAM should be always fully utilized. You paid for it, you're paying to keep it powered up, it's really counterproductive for all this money to go to waste.

If your computer feels slow right after updating, it's true that the indexing service may be to blame. Let it stay on overnight, make sure you get a full Time Machine backup done, and see what transpires next. Don't get hung up over RAM consumption - without some rather technical understanding of what those numbers mean, you can't make any use of them. They are red herring. It's a curiously recurring pattern.

  • No indexing is done. Still having issues at times with unresponsive or slow/delay system response on Mac mini. MBP seems to have faired better after a few days of installing Mavericks, yet the Mac mini lags at times
    – bretonics
    Oct 30, 2013 at 17:46
  • It might be the apps you're using in particular that might be slow if they're optimized for the last version of OS X. I'd try running comparisons on Apple apps like Safari. Nov 1, 2013 at 5:24
  • Looking at the activity monitor, which lead me here, my late 2013 MBP is using apprx 13 out of 16GB RAM. Although I don't notice any performance issues as others have mentioned. Catching a glimpse of the pinwheel is like seeing the Sasquatch.. There it is!! I think... It just seemed unusual being that I really didn't have anything running. But this is my first Apple product so just thought I'd check. plus 1 for clear and concise answer.
    – derelict
    Mar 3, 2014 at 23:15
  • 2
    @SoilSciGuy Ideally you should have all of your RAM used up. That RAM is buffering the hard drive - it's always faster than the drive, even if the drive is an SSD. Whatever RAM is unused is a waste of power and money. Mar 3, 2014 at 23:17
  • I would second this answer emphatically. Memory usage on Mavericks is quite different than past OS X in how it represents usage to end users (and to experts alike). Using all the RAM is a good thing. If people have issues with slowness, ask that question and we can show if RAM is the cause of the slowness, but this question is nice since the initial impression might be that things are broken when it's just a change that was intended with OS X 10.9.
    – bmike
    Mar 4, 2014 at 13:12

Have you checked if Spotlight is indexing the hard drive?

I found that for about 2 hours after installing Mavericks, my computers needed to perform this task, which took up a lot of system resources.

You can disable this indexing (guide here) and check whether it freed up any memory, which has been suggested by some to be the case in similar situations.


I am having the same problem, but also seeing a degradation in performance, system hangs and app crashes. I do photography and some of those apps, especially Lightroom, NEVER give up memory that they have taken, even after you quit them!

I talked to mac support and was told that if you open your apps to full screen/maximize, everything behind them will go into app nap mode. He said that is the best way to take advantage of Maverick memory capabilities - let each app take the whole screen and ctrl-tab between them. Unfortunately, that is not how I work,and doesn't work well for my needs. It might help you out tho.

I used to be able to do a "purge" from a terminal app and clear out unused memory, but maverick does not allow me to do that anymore. I would keep an eye on memory and just type purge now and then and things were fine. I am searching for a way to do that in Maverick. If not, I may have to do a restore from time machine as I am unable to do my work.

I installed Maverick more than 5 days ago so I would think it should be done indexing. macbook retina pro, 16gb, kernal is using 1.13gb, page file is about 8Gb.

  • The same thing happens to me, my iMac freezes for about 30 seconds, and then tries to catch up repeating anything I have been pressing or doing while waiting.
    – Mark Ellul
    Nov 4, 2013 at 16:44

RAM is there to be used. It is a place for your computer to keep the most frequently used data so it doesn't have to fetch it from disk which is much slower (could be 50-60 times slower). The RAM in your Mac Mini is 1600MHz DDR3 if you upgraded at time of purchasing. This is capable of about 12800MB/s transfer. The HDD if it's a physical one is a 5400rpm drive capable of 200-300MB/s. So you want your RAM to be fully utilised. It's no use to you when it's free.

With that in mind, your problem is not how much RAM is in use but rather, why your computer is slow. The best way to determine that is to see which programs are accessing the HDD. You can read all about how OSX manages memory on Apples support site.

As pointed out in this Superuser answer:

Mavericks introduced "memory compression" which is, more or less, another layer of swap. Active pages now get classified inactive, then compressed (which might show up as Kernel memory depending on what tools you are using,) then written to swap as memory usage increases. Mavericks has also has stopped showing separate numbers for active and inactive in Activity Monitor, since it turns out not to be a useful thing to look at, especially given the misconceptions surrounding it.

As suggested by other people, a hard-drive index or full system backup would be a major culprit of disk activity slowing your machine so I'd look there first. You can also disable the spotlight indexing in Terminal if you wish like so:

Disable: sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

Enable: sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

I would try turning off indexing temporarily, perform a full backup, when you've done both of those then re-assess the performance of your Mac and if you still have issues then use Activity Monitor to see what else is performing Disk I/O.


I have the same problem, and I want to clarify one point the TS/OP mentions; the activity window doesn't account for all the ram that is used. Combined, the stuff showing in the window doesn't add up to the crazy amount being used some where secret...

My answer would be, let time pass and see if it'll go away by itself, there might indexing or updating going on under the hood.

  • This seems like it would work better as a comment on the original post, since it is not really an answer per se.
    – tubedogg
    Oct 25, 2013 at 0:11
  • @tubedogg Actually, the real problem here is the question. It's so vague it's hard to turn away anyone's opinion or experience. The core of this answer is to wait for indexing and other processes to end which might help some people.
    – bmike
    Mar 4, 2014 at 13:08

Others have asked, but how are you determining RAM usage? Via top in the command line, I see the following on my Mac Mini (2012) with 8GB of RAM:

PhysMem: 3861M used (919M wired), 4328M unused

Which seems right. But if I run htop—which is an improved version of top I have compiled & installed on my own—I see the following.


Which to me reads as if I am only 512MB away from swapping. Which is all to say that you might be reading the data incorrectly & something else on your setup is causing a bottleneck. I’m quite happy with the speed & responsiveness of Mac OS X 10.9 on my setup. No issues. More stable than Mac OS X 10.8.


Memory clean app sovled my problem.


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