Which iMac specs most important for Lightroom?

Discussion in 'iMac' started by jordanneo, Jun 27, 2016.

  1. jordanneo macrumors newbie

    Oct 29, 2012

    I'm thinking of buying a 27" iMac and my most intensive computer tasks are in Lightroom. Which specs are worth paying to upgrade to get the most improved Lightroom performance?

    Fusion drive?

    My current PC is an HP running Windows 10 (originally came with 7), i7-2600 CPU @ 3.4 GHz, 10 GB RAM and AMD Radeon 6570. I bought it in late 2011.


  2. Bubba Satori Suspended

    Bubba Satori

    Feb 15, 2008
    1. 32GB Ram. Don't buy from Apple.*
    2. 1TB SSD. Don't buy from Apple.*
    3. Fastest CPU you can afford.
    4. GPU with the most memory to drive the 5K display.

    If you don't need the iMac right now, new ones should be out in August or September.
    Hth and good luck.

  3. maflynn Moderator


    Staff Member

    May 3, 2009
    I'd recommend the base ram, and upgrade after using LR. I have 8GB and I don't find LR to be problematic with that memory size. I also have the M395 GPU model, and that gives me some nice pep for the GPU and CPU.

    Where you're going to feel the burn is the Fusion drive, if you're looking for performance, configure the iMAc with a SSD. I have the 2TB Fusion drive and its a nice unit, but I do feel LR slowing doing as the spinning hard drive accesses the catalog/images.
  4. jordanneo thread starter macrumors newbie

    Oct 29, 2012
    Thanks very much for the replies.

    What is so much better about a pure SSD versus Fusion? I thought Fusion was supposed to move things like the Lightroom catalog to SSD to make processing as fast as possible.

    Also, and I totally am not trying to start any PC vs Mac stuff here, what do you think of this article comparing iMac to PC performance specific to Lightroom? https://www.slrlounge.com/lightroom-mac-vs-pc-speed-test-4k-imac-vs-4k-custom-pc-performance-test/

    If I do buy the top spec iMac, is it going to fly?


  5. Apple fanboy macrumors Penryn

    Apple fanboy

    Feb 21, 2012
    Behind the Lens, UK
    Currently using a late 2012 iMac with 1TB Fusion Drive and 16GB RAM and an i5 Processor.
    LR is still plenty quick enough on these specs, so you should be fine.
    RAM you can upgrade later, so pay for the things now you can't easily change when you buy like the GPU/CPU.
  6. joema2 macrumors 65816


    Sep 3, 2013
    The article is basically accurate. A custom-built, liquid-cooled overclocked PC with an 8-core CPU will be much faster on Lightroom than a top-spec factory iMac 27. To a large degree this is because of how slow and inefficient the Lightroom code is.

    I imported the same set of 42 megapixel raw stills from my A7RII into both Apple Photos 1.5 and Lightroom CC. With LR using previously-built 1:1 previews, the full-screen browsing rate in the Library module is about 0.81 photos per second, IOW 1.2 sec per photo.

    In Apple Photos, the full-screen browsing rate is 6.4 photos per second, or about 7.9 times faster. This is on the exact same machine, a 2015 top-spec iMac 27 with 1TB SSD and M395X. This is roughly in line with some performance differences between Premiere CC and FCPX. The FCPX frame update rate when scrubbing a H264 4K timeline is much faster, and FCPX exports H264 about five times faster than Premiere.

    The Adobe Lightroom product manager has recently publically apologized about the poor quality of their software. It is so bad that *disabling* the GPU in LR preferences will often speed up the operation. That is not a slow GPU, it is poorly written and poorly optimized code.

    If you don't use high-megapixel raw stills you may not notice the difference. But if you are a professional wedding or event photographer and shoot thousands of high-megapixel raw stills per session, even a top-spec 2015 iMac 27 can periodically feel a bit pokey on Lightroom. The bottleneck is not in the disk subsystem and even a Thunderbolt SSD RAID 0 array will not help. It is largely inefficient code in Lightroom.

    In this demonstration Adobe showed 8x performance improvements in After Effects by using Apple's Metal API, and Adobe committed to bringing this to Photoshop and other Adobe products. They have since backpedaled on this, and it is unclear if these enhancements using the Metal API will ever appear:

    You can compensate by using a hugely powerful custom-built PC, which is not an option for a Mac unless you build a Hackintosh.
  7. robgendreau macrumors 68040

    Jul 13, 2008
    Yeah, I expect the PC would be faster. If doing those tasks is important maybe no Mac for you.

    OTOH that PC rig is running a 2.5k monitor. Color accurate, sure. But like looking through a screen door. I save TONS of time on the 5k cuz I don't have to zoom as much, and see 4x as much in 1:1 as the 2.5k. If you can live with a fast CPU and doddering old display tech, go for it.
  8. jordanneo thread starter macrumors newbie

    Oct 29, 2012
    Thanks very much for the info. Still lots to think about. I'm starting to think that I shouldn't be trying to configure a machine solely around Lightroom. But I do want to make sure that I don't end up with a machine that is sluggish in Lightroom because I spend so much time in it. And I definitely appreciate the point about the 5K monitor making zooming less necessary. The native "fit" option is going to be bigger than what I publish in jpeg today.

    I'm still wrapping my head around what is so much better about a pure SSD versus Fusion? I thought Fusion was supposed to move things like the Lightroom catalog to SSD to make processing as fast as possible. I'm used to working with attached external storage since RAW files, etc, take up so much space. I was hoping that a 3TB Fusion would be the best of both worlds versus having to manage what's on a small, .5-1 TB SSD.

    And any believable (to you) rumours about what will be in the next iMac refresh?

    Thanks again!

  9. Samuelsan2001 macrumors 604

    Oct 24, 2013
    A fusion drive only has 24gb flash on the 1 TB and 128gb of flash on the 2 and 3tb versions,so once your most used apps and OS X are on the SSD there is no room to load all those raw files to SSD when you need it,so most of your files will be on the HDD.

    Your best bet though would be to buy the 2 tb fusion, remove the HDD and add a SATA 3 SSD like a samsung 950 pro 1tb and reinstate fusion then you'll have full flash at a reasonable price and a super fast PCIe SSD running apps and OS. Of course opening up a brand new iMac is a bit of risk.

    Of course you could just get a 256gb flash iMac and use an external SSD for your files as the easiest option.
  10. joema2 macrumors 65816


    Sep 3, 2013
    I have both 2013 iMac 27 with 3TB Fusion and 2015 iMac 27 with 1TB SSD. I do a lot of video and still editing with Lightroom, Premiere CC and FCPX. For many workflows there is little difference between SSD and 2 or 3TB Fusion. The most time-consuming workloads are often CPU or GPU bound (usually CPU). You are waiting on the CPU and infinitely fast I/O will not help much. Anybody can see this themselves by doing an import of raw stills and 1:1 preview generation in Lightroom or transcode/export in Premiere or FCPX, while monitoring CPU with Activity Monitor or iStat Menus.. Those are not I/O bound operations, nor are most others.

    That said, having SSD does help a bit on some things and if you already have most of your media on fast external storage, why not get SSD. It's one less thing to worry about performance-wise and, reliability is probably a bit better.

    Re using external SSD, if you are an experienced photographer using high megapixel raw stills this is often not an economically viable option. You can easily shoot 100GB per day, and using Lightroom 1:1 previews (which you often need for performance) roughly doubles that to 200GB.

    It sounds like you are not dabbling with little JPGs on an iPhone, so you will need (or already have) large high performance external rotating storage. But if you can afford several terabytes of Thunderbolt SSD, plus the additional storage to back that up, then go ahead. It won't help your Lightroom performance much but you can at least move files around faster.

    Re the article you referenced comparing a custom-built PC vs an iMac, the opposite is also true. You can have a custom builder make you a Hackintosh with high-end components and compare that to a factory-built all-in-one PC like a Dell XPS 27. The custom-build Hackintosh will be vastly faster than the factory-built all-in-one PC.
  11. robgendreau macrumors 68040

    Jul 13, 2008
    My previews and Lr catalog can take up to 100GB+. I don't have proof, but I'd suspect that Fusion wouldn't put all that on the SSD. And so there might be some slowdown associated with the Fusion. But it certainly wouldn't be FASTER than a SSD.

    And consider that the tradeoff is no big deal. If you have to put archived or just rather infrequently used photos on an external HDD via USB you aren't gonna take a huge hit. Sure, if Lr has to fetch a few on the fly that it doesn't have previews for it will take a bit. OTOH if you knew you had to edit a folder of 2013 shots you could just move 'em over from the external and generate new 1:1s, and get a cup of coffee. Distinguish bulk operations that you don't have to pay attention to vs things like redraws or lags while say developing one photo.

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