Is Mavericks/Yosemite new RAM management slower than before?

Discussion in 'macOS' started by poiihy, Oct 30, 2014.

  1. poiihy macrumors 68020


    Aug 22, 2014
    Before Mavericks, the OS would just dump excess memory in swap. But with the new memory management, rather than dump it, it compresses and cleans as much as it can, and only swaps when it really has to. I would think this would be slower than just dumping it in swap. There's usually plenty of disk space for swap.
    My two 2009 Macs have 2GB ram until I get more (one had defective ram and i had to share), and Mavericks/Yosemite is very slow on them. I use leopard on the MacBook pro (on 20gb partition) and it is very much faster, but many new things dont work.
    I've heard that you can disable the compressed memory or virtual memory in terminal. Would this make it faster?
  2. chown33 macrumors 604

    Aug 9, 2009
    Sailing beyond the sunset
    Yyou have a hypothesis, so do an experiment to collect evidence.

    Which do you think is faster in MB/sec, performing disk I/O, or performing in-memory compression? If you think disk I/O is faster, then you should do some disk bandwidth and compression-speed tests to prove this. If you think in-memory compression is faster, then you already have the answer of why the OS chooses compression before disk I/O.

    If you just want someone to tell you the answer, then the OS engineers already did that.
  3. Fishrrman, Nov 2, 2014
    Last edited: Nov 2, 2014

    Fishrrman macrumors G5


    Feb 20, 2009
    I believe the OP is correct -- that is to say, the overall paradigm of how the OS "handles memory" -IS- slower in Mavericks (a little less so in Yosemite).
    From the viewpoint of the software engineers at Apple who designed it, it may be "better", but nevertheless it -is- "slower".

    This is particularly noticeable to the user, if the user is still using an older hard disk drive with spinning platters. I've seen numerous posts from others about this, I'm not the only one.

    BUT -- the use of an SSD, or a fusion drive (SSD+HDD) provides enough residual speed so that the slowdowns are minimized and made "un-noticeable".

    I totally gave up on Mavericks. I was experimenting with it using an old 2.5" IDE drive mounted in a firewire400 enclosure, and the "lags" were terrible. Not a workable installation, in my opinion.

    However, the same hardware performs considerably better using Yosemite. I have to say I was surprised, actually pleased.
    I have made a few changes via terminal to "tweak" Yosemite to my liking:
    - turned VM -COMPLETELY OFF-. No VM at all, no swap files at all!
    - disabled compressed memory
    - disabled Spotlight completely and removed all index files
    - disabled the sleep image file.

    I realize it can be inadvisable to disable VM in any setup where the swap file may be needed, but I bumped up the installed RAM in my 2012 Mac Mini from 4gb to 10gb, and I'm not one of those guys who fills up Safari with 50 tabs (I don't use tabs AT ALL), or who loads up 20 applications at once.
    So far, so good.

    But again, the OP is onto something regarding the change in how RAM is loaded and managed in Mavericks and Yosemite. I sense that Apple's developers designed both OS's on newer, highly-powered Macs, just about all of them using SSD's or fusion drives.

    Yes, the OS's will run on less-powerful Macs with HDD's.
    BUT -- they just won't run very fast!
  4. chabig macrumors 601

    Sep 6, 2002
    On the contrary, the less powerful the Mac, the more advantagous memory compression is over disk I/O.
  5. poiihy thread starter macrumors 68020


    Aug 22, 2014
    Even the Yosemite boot progress bar does not match older Macs; they are designed for SSD Macs. Does any developer there even use an older Mac?

    I had a 2006 MacBook Pro with the original 1GB ram and I remember it was faster on Snow Leopard than my current 2009 MBP with 2GB with Yosemite.


    So what would be the best OS for a 2009 MacBook Pro with 2 GB of RAM; a balance between compatibility and performance?
    I wish I had a Snow Leopard disk :(
  6. Fishrrman macrumors G5


    Feb 20, 2009
    poiihy asked above:
    [[ So what would be the best OS for a 2009 MacBook Pro with 2 GB of RAM; a balance between compatibility and performance? ]]

    That answer is easy-peasy.

    OS 10.8.5 "Mountain Lion".

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