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Author Topic: Are Lightroom and Photoshop highly multithreaded or not?  (Read 4513 times)
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« on: December 19, 2013, 05:39:08 AM »

Which processor is optimal for running PS and LR with the new Mac Pro?

The Apple Store says "if you run apps that are not highly multithreaded, you will benefit the most from processors with a higher clock speed. Highly multithreaded applications will perform best on processors with a higher core count, even with a slightly lower clock speed."

  • Is LR highly multithreaded?
  • Is PS highly multithreaded?

If they are highly multithreaded then it seems that the extra money for the 12-core processor might be worthwhile even though it has a slower clock speed and costs more.


Henry Domke Fine Art
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« Reply #1 on: December 19, 2013, 05:57:54 AM »

Someone more knowledgeable will likely chime in I hope - but my understanding is that neither LR or PS will take advantage of 12 cores. I doubt they even take full advantage of 8-cores. The multi threading in PS and LR seems to me at least in my experience to be half baked at best.

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« Reply #2 on: December 19, 2013, 06:21:22 AM »

It used to be that if I exported 100 images, Lightroom would tax one of my cores 100%, and none of the others. The work-around was to trigger N exports of 100/N images at the same time.

In LR 5.x, it seems that my (4 physical, 8 logical) cores are working at high load, indicating that at least the export task is threaded to at least 8 threads. I don't see why Adobe would limit this number to anything less than the minimum of (#logical cores, #images to export).

For other bottle-necks, like moving a slider in development mode, I am not sure how well threaded LR is. That would be more implementation work, I guess.

The speed improvement that is most likely to affect most software applications is bumping the cpu clock, as this puts no demands on the software developers. Unfortunately, Intel & friends struggle to deliver this, and threading seems to be one alternative that they can deliver.

« Last Edit: December 19, 2013, 06:23:34 AM by hjulenissen » Logged
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« Reply #3 on: December 19, 2013, 07:45:26 AM »

I believe one of the best sources of information regarding all things Mac and how they pertain to the needs of photographers is Lloyd Chambers’ site ‘Mac Performance Guide’ (  His own testing has shown basically what Josh Holko also mentions in his post, namely that LR and PS can’t really take advantage of such high-core CPU’s.  Though his testing of the new Mac Pro hasn’t yet begun, he tends to believe the 6-core version is probably the ‘sweet spot’ for most LR and PS users.

With Best Regards,

Lawrence Braunstein
« Last Edit: December 19, 2013, 10:25:38 AM by LawrenceBraunstein » Logged

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« Reply #4 on: February 02, 2014, 04:33:42 PM »

Here is the logic I used in my decision-making with regard to which Mac Pro model to buy.

Imports and most importantly preview rendering are most definitely multithreaded. I see no reason why Adobe would limit it to just 6 or 8 cores, and I would imagine if that limit existed, it's arbitrary and trivial to remove if Adobe so wanted to.

Running up extra cores takes a little time and effort, and so while the extra core would be useful in the editing workflow of Lightroom and Photoshop, core count is probably not as critical since the operations are relatively short-lived. By the time you get a thread going, and started to process a brush stroke, for example, most of it could be done with a single thread.

Also remember that input/output is part of the equation - and could be an important bounding factor on preview generation. You may have a dozen cores rendering previews, but they all have to go through a single I/O controller.

So, I went for the 6-core model because the clock rate of the processors is higher, and would give me a small advantage in editing (brushing local adjustments, spot removal, etc). I can wait a few extra minutes for preview rendering. Not to mention it saved me $3,000 - which I put toward more static RAM, which, as per my I/O argument above, is the shortest path to high performance.

Regardless of your choice, you're not likely to be disappointed. It's going to be a very nice machine to use.

-- Mike
« Last Edit: February 02, 2014, 04:37:07 PM by utahmike » Logged

Michael Clark - Salt Lake City
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