iMac retina REDUX - please test your 27"- lags in Preview

Discussion in 'iMac' started by trayloader, Nov 11, 2015.

  1. trayloader, Nov 11, 2015
    Last edited: Nov 11, 2015

    trayloader macrumors member

    Sep 13, 2007
    Hi dear iMac users,

    I bought a 2014 27" 3.5Ghz i5 model, shortly before the refresh.
    Running 10.10.5 with 16GB RAM.

    Coming from a 2011 3.4 i7
    I found it always relatively slow.
    Photoshop lags, so does Lightroom.
    Everything used to be much more snappy on the old machine.

    Today I got a file from a photographer seeing the same behaviour, and this finally sealed my observations.
    It´s a ~500MB file (after opening) and it brings Preview to its knees.Sliders have an unbearble lag.

    Please download the Photo , test in OSX PREVIEW there color correction sliders and report back:

    I´d like to know what´s the culprit, if it´s a performance problem,Yosemite, etc.

    thank You
  2. fa8362 macrumors 65816

    Jul 7, 2008
    It could be a variety of things (including non-optimization of software), but pushing all those 5K pixels around is definitely not helping.
  3. AlexGraphicD macrumors 6502


    Oct 26, 2015
    New York
    Then why the heck apple puts out in the market a machine that can't properly handle its own screen pixels?
    I am not an expert in PC's and performance in general but as I read a lot about how the 5k's being laggy with the screen pixels and all that, I wonder why does apple put subpar GPU on the 5k line?
  4. fa8362 macrumors 65816

    Jul 7, 2008
    A variety of reasons, but one of them is that most people aren't using 500 MB images.
  5. AlexGraphicD macrumors 6502


    Oct 26, 2015
    New York
    Well I read a lot that the 5k gets laggy with smaller files than 500MB...
    From the little I've learned the problem lies to the GPU which is used in mobile phones or something, is that right?
  6. fa8362 macrumors 65816

    Jul 7, 2008
    It's a laptop gpu, not a mobile phone gpu. The thin design iMacs have always used laptop gpus. Desktop gpus aren't appropriate for the slim design.
  7. joema2 macrumors 68000


    Sep 3, 2013

    I downloaded and tested in LR CC 2015.1.1 on OS X 10.11.1, 2015 iMac 27, 4Ghz i7, 32GB, 1TB SSD, M395X.

    It mostly is OK, all the sliders in the develop module are fluid and fast. However using an Adjustment brush has a little lag. I then turned off GPU acceleration in LR Preferences>Performance>Use Graphic Processor -- the adjustment brush lag mostly went away.

    This does *not* indicate there's some kind of deficiency with the GPU, rather Adobe's software is messed up. LightRoom manager Tom Hogarty recently apologized and said their quality has failed on multiple fronts:

    This is obvious because other software such as Aperture and FCP X is not laggy and slow when running on the same hardware.
  8. trayloader thread starter macrumors member

    Sep 13, 2007
    To ALL again:

    please test in OSX "PREVIEW" app.

    and 500MB is not huge.
  9. fa8362 macrumors 65816

    Jul 7, 2008
    That's not realistic. Trying to view 500 MB images in Preview is not at all common behavior. Professionals don't use Preview and amateurs don't typically use 500 MB images.
  10. trayloader thread starter macrumors member

    Sep 13, 2007
    I beg to differ here.This is not a wimpy consumer machine.
  11. joema2 macrumors 68000


    Sep 3, 2013

    I tested it in OS X Preview on these Macs running OS X 10.11.1:

    - 2015 iMac 27 4ghz i7, 32GB, 1TB SSD, M395X
    - 2013 iMac 27, 3.5Ghz i7, 32TB, 3TB Fusion Drive, GTX-780m

    And on this Mac running 10.10.5:

    - 2015 MacBook Pro, 2.8Ghz i7, 16GB, 1TB SSD, M370X

    On both computers running 10.11.1, the color sliders in Preview were very sluggish. Preview crashed several times.

    On the MBP running 10.10.5, it was less sluggish and Preview didn't crash but would grey out the screen and I couldn't see it unless I closed the file and inspected it with Quick Look or another app.

    Conclusions: the behavior does not seem related to the 5K screen or AMD GPU. It is more related to the OS version, coupled with an extreme size file that typically is not manipulated in Preview.

    Preview should never crash, nor grey out the screen, so that is a clear software problem. It should exhibit "graceful degradation" as the file size increases. The very sluggish slider behavior is not ideal. However this is an "edge case" of an extremely large file manipulated with an app that's not really designed for that.

    However it is possible the slow Preview slider behavior is not isolated to this one app but leads to deeper system-layer issues needed further optimization. That would be a good thing for Apple to investigate.
  12. DaakuMaujii macrumors member


    Oct 25, 2015
    I doubt it's the machine, but rather the software. Preview has alway be mediocre in performance. There are PDFs with vector graphics that make scrolling through articles slow down to a crawl. Unfortunately Acrobat Reader is not much better. Try El Capitan, Apple claims speed improvements of their applications: "up to 4x faster PDF opening in Preview". It just shows how much these utilities applications that ship with OS X have been neglected in performance and features, especially in uses cases not typical to the average consumer viewing 8 to 12 megapixel holiday pictures.

    EDIT: for what it's worth: adjusting the color settings on my Macbook Pro Retina running 10.11.1, it takes about 4 to 5 seconds before the changes take effect. It is a quite CPU intensive process, maybe not optimised to take effect of the GPU.
  13. trayloader thread starter macrumors member

    Sep 13, 2007
    IMHO that´s catastrophic.I thought it may have been the video card, or maybe Yosemite but witnessing the same behaviour on the 2015 iMacs, I think it´s time to bring it on Apples radar.
    I just feedbacked them.

    Let´s investigate further.
  14. desmond2046 macrumors regular


    Jun 2, 2015
    Columbus, OH, United States
    I want a mobile phone with Tonga GPU!

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13 November 11, 2015