# Quad Core vs Dual Core



## artmaltman

Do any of you know whether quad core is an advantage over dual core when it comes to editing photographs in Lightroom and Photoshop?

I'm debating MacBook pro 13" (dual) vs 15" (quad) and really, I'd rather have the smaller one. The issue is whether the quad core would make Photoshop and Lightroom run noticeably faster when editing photographs. I get into very detailed editing on headshot. Lightroom in particular will bog down tremendously sometimes.

All of my software is most current version, always. Currently using a 2015 MBPr 13" maxed out I7 16gig memory. Considering the latest (2017) MBPr models.

My impression is that Photoshop and Lightroom use only one core, so what matters more is the speed of that one core, in which case the 13" at 3.5mhz is actually faster.

SO, do any of you know whether quad core is an advantage over dual core when it comes to editing photographs in Lightroom and Photoshop?

Thanks!

Art

ps: I have read that use of the dedicated GPU on a 15" would actually slow down these programs when editing photographs. That it's best to turn off the dedicated GPU. Have any of you confirmed that via testing?


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## Hal P Anderson

I just tried a _really_ mickey mouse experiment on my quad-core i7. Brought up Windows Task Manager and watched the CPU graphs as I ran the Exposure slider back and forth, back and forth. All 8 of the CPU graphs (I have hyperthreading) hovered around the 50% mark. So I guess it uses all the cores, but doesn't seem to max them out. It could be that Adobe throttle back to 50% per core so it doesn't hog all the CPU cycles. 

On the other hand, creating previews and exporting will run all the cores at 100%.

I find that enabling the GPU doesn't seem to make things either faster or slower on my machine. I leave it on, though.


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## artmaltman

Hal P Anderson said:


> I just tried a _really_ mickey mouse experiment on my quad-core i7. Brought up Windows Task Manager and watched the CPU graphs as I ran the Exposure slider back and forth, back and forth. All 8 of the CPU graphs (I have hyperthreading) hovered around the 50% mark. So I guess it uses all the cores, but doesn't seem to max them out. It could be that Adobe throttle back to 50% per core so it doesn't hog all the CPU cycles.
> 
> On the other hand, creating previews and exporting will run all the cores at 100%.
> 
> I find that enabling the GPU doesn't seem to make things either faster or slower on my machine. I leave it on, though.



Thanks for doing this!   It sounds like a definitive test.


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## Hal P Anderson

Don't put a lot of faith in it. Lightroom has always performed well for me, but people with truly awesome machines sometimes come to these forums with tales of horrendous slowness. That said, if I were you, I'd go with the 4-core.


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## Zenon

Adobe has announced a major performance update coming with 7.2. Seems geared for expensive machines. Tested on 8 + cores and 32 +64GB rams for both Mac and PC but says if you have 12GB ram you will see a difference. We shall see.


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## tspear

With Lr 5.X; I think the dual core would have been better.
Since Lr 6.X when they added the initial GPU support, each patch/version has incrementally improved the multi-core functionality.
On my Windows machine with Lr 7.1, AMD Ryzen 1700 with 8 cores with a 1060 GPU; I can see many of the basic adjustments use multiple cores. Especially with local adjustments. The more local adjustments you have the more Lr seems to spread the load. While some functions like playing with the tone curve yielding one or two cores working.

Tim


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## clee01l

I have both a dual core rMBP (8GB)  and a quad core iMac with 32GB  The rMBP struggles but can do an adequate job for a laptop but I would not want to depend upon it for my only machine. If you do a lot of photo processing I'd recommend a desktop over a laptop

LR has been shown to use up to 6 cores if available  and  always makes heavy use of the cores available.


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## PhilBurton

Zenon said:


> Adobe has announced a major performance update coming with 7.2. Seems geared for expensive machines. Tested on 8 + cores and 32 +64GB rams for both Mac and PC but says if you have 12GB ram you will see a difference. We shall see.


Yes, and if these performance improvements require a beefy system, maybe it's time to upgrade.


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## Ian.B

still on the performance thing: i5 or i7 ?? . I have heard i7 has far more benefits in video/gaming/and the likes than photo editing.
My Acer laptop is i5 and seems good enough. The older ASUS is i7.  
I'm over laptops and will likely move back to a PC very soon ---- will likely sell the two laptops and get a small 'travel' laptop. 
Yeah; _MORE $$$_ into a hobby; and a 1/2 interesting hobby at that atm --- too hot here with temps of 40-44c not uncommon


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## Zenon

PhilBurton said:


> Yes, and if these performance improvements require a beefy system, maybe it's time to upgrade.



They must in cahoots with the computer manufacturers.  Ain't gonna happen until it's time to happen.


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## Zenon

I'm not that savvy with this stuff so I'm going to ask a dumb question. How do I know ow many cores it has? I see Intel Core i5.


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## Zenon

I just did a random search and it appears to be 4. So I guess dual gives you 8 and so on? I did upgrade from 8 to 16MG ram last month on my iMac.


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## artmaltman

Zenon said:


> I just did a random search and it appears to be 4. So I guess dual gives you 8 and so on? I did upgrade from 8 to 16MG ram last month on my iMac.



The MacBook Pro 13" have dual core and the MacBook Pro 15" have quad core.  Generally for any machine you have to look up the specs and it should tell you.


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## Zenon

OK thanks. I was looking in the About This Mac but it does not specify anywhere. I'll find it. Gives me something to do.


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## tspear

Ian.B said:


> still on the performance thing: i5 or i7 ?? . I have heard i7 has far more benefits in video/gaming/and the likes than photo editing.
> My Acer laptop is i5 and seems good enough. The older ASUS is i7.
> I'm over laptops and will likely move back to a PC very soon ---- will likely sell the two laptops and get a small 'travel' laptop.
> Yeah; _MORE $$$_ into a hobby; and a 1/2 interesting hobby at that atm --- too hot here with temps of 40-44c not uncommon



i5 or i7, which generation?
That can make a big difference depending on the tasks.

Tim


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## Zenon

I noticed that there were generations but still have not figured it out.


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## clee01l

Zenon said:


> I'm not that savvy with this stuff so I'm going to ask a dumb question. How do I know ow many cores it has? I see Intel Core i5.


Open Task Manager. Select the Performance tab to see *how many cores* and logical processors your PC has.

Oops! You have a Mac:
Open Activity monitor, then from the menu {Window}Click on {CPU History}.  Each graph is activity on one of your CPU Cores


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## Conrad Chavez

Zenon said:


> OK thanks. I was looking in the About This Mac but it does not specify anywhere.


When you're in About This Mac, click the System Report button. That opens the System Information utility. Make sure Hardware is selected in the left column (it should be selected by default), and in the panel on the right, the Hardware Overview will show details about your processor.

For my Mac, it says, among other things:
Processor Name:    Intel Core i7
Processor Speed:    2.2 GHz
Number of Processors:    1
Total Number of Cores:    4


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## Zenon

There it is. Right in front of me. I can't believe I didn't see it. I am not enjoying these golden years. All those commercials I watched when I was 25 and before PVR were full if it. Thanks.

1 processor - 4 cores


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## sizzlingbadger

I have a 15" and 13" MacBook Pro and I don't really notice much difference in performance, however, I do prefer the 15" screen and would choose it every time over the 13" for Lightroom.


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## tspear

Zenon said:


> I noticed that there were generations but still have not figured it out.



Depending on who you believe, each generation has about a 20% improvement in performance; except the jump to Gen 7 (the most recent one). Most of the stuff I have seen shows a 40% increase in performance. 
The end result, for many users a Gen 7 i5 Core is faster then a Gen 5 i7 Core.... just to confuse matters... 

Tim


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## LouieSherwin

Hi Art,

So much depends on how you intend to use your system. For example are you a casual photographer shooting JPG family and travel photos or are you an event photographer needing to process hundreds of raw images over night? For the former a MacBook Air might be more than enough but for the latter you will need some serious compute power. 

If you process primarily raw then the size of the image files that you are now using and the size of images for any intended camera upgrades that you have planned should be considered. A system that performs well on 20MP files could easily start to lag when trying to process high resolution 36-50 MP files.

Another thing to keep in mind is that multiple cores can only help for processes that can be parallelized. This can be easy for things like Import and Export where Lightroom can send each image to a different core. However it is not so easy with things like the Develop module where there is a pipeline of complex matrix math that has to be applied in sequence to the entire image. 

The upshot of this is that the number of cores mater for some things but not necessarily for others. The latest information I have heard is that Lightroom 6 (Classic) can only take advantage of 6 cores at most although this may be changing. 

I think that the current best advice is to get the get a system with the fastest CPU, most RAM and fastest disk that you can reasonably afford with something like 4-6 cores.  I currently have a MacBook Pro  15" 2011 2GHz Intel Core i7 (4 cores), 16MB RAM, 512GB SSD and internal 500GB 7200 RPM HD. I can run Lightroom Classic and Photoshop CC simultaneously with no problem. 

This works quite acceptably with my Sony A7R2 for my landscape and personal work while traveling though I don't think I would be happy with this as my main system.  A big issue is the limited gamut of the laptop screen when trying to work on detailed image editing. I would highly recommend a wide gamut display, NEC or Eizo if you want to do any serious gallery level printing. 

I hope that this was helpful.

-louie


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## Ian.B

tspear said:


> i5 or i7, which generation?
> That can make a big difference depending on the tasks.
> 
> Tim


Don't get too technical Tim  . Put it this way; the i5 Acer is 12 months old
This is easier 



I certainly don't have any Lr5 dramas; although On1 can be slow saving files; but that's On1!


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## David Gordon

clee01l said:


> Open Activity monitor, then from the menu {Window}Click on {CPU History}.  Each graph is activity on one of your CPU Cores



Top tip! I can see four graphs, so I must have four cores. But "About this Mac" says I have one processor and a total of two cores...


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## Hal P Anderson

David,

On my Windows machine, I have 4 cores and Task Manager shows 8 graphs. Your extra graphs are probably from hyperthreading which acts kind of like extra cores. 

Hyper-threading - Wikipedia


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## artmaltman

Do any of you know whether quad core is an advantage over dual core when it comes to editing photographs in Lightroom and Photoshop?

I'm debating MacBook pro 13" (dual) vs 15" (quad) and really, I'd rather have the smaller one. The issue is whether the quad core would make Photoshop and Lightroom run noticeably faster when editing photographs. I get into very detailed editing on headshot. Lightroom in particular will bog down tremendously sometimes.

All of my software is most current version, always. Currently using a 2015 MBPr 13" maxed out I7 16gig memory. Considering the latest (2017) MBPr models.

My impression is that Photoshop and Lightroom use only one core, so what matters more is the speed of that one core, in which case the 13" at 3.5mhz is actually faster.

SO, do any of you know whether quad core is an advantage over dual core when it comes to editing photographs in Lightroom and Photoshop?

Thanks!

Art

ps: I have read that use of the dedicated GPU on a 15" would actually slow down these programs when editing photographs. That it's best to turn off the dedicated GPU. Have any of you confirmed that via testing?


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## Linwood Ferguson

David Gordon said:


> Top tip! I can see four graphs, so I must have four cores. But "About this Mac" says I have one processor and a total of two cores...


As Hal mentions that likely means Hyper Threading is on. This is controlled in your bios, not in windows.  The normal default is on, as it makes systems "look" more substantial than otherwise.

In days past it was questionable whether HyperThreading was a good thing, but with LR 7.1 and soon to be released 7.2, HyperThreading is a good thing, as Adobe counts cores and does not turn on certain optimizations unless you have enough.  Four is sadly probably not enough for much of the performance benefit that they are working on.  Four is better than two (so on is better than off), but four is not where you see the real benefit from the new lightroom performance changes.


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## PhilBurton

Ferguson said:


> As Hal mentions that likely means Hyper Threading is on. This is controlled in your bios, not in windows.  The normal default is on, as it makes systems "look" more substantial than otherwise.
> 
> In days past it was questionable whether HyperThreading was a good thing, but with LR 7.1 and soon to be released 7.2, HyperThreading is a good thing, as Adobe counts cores and does not turn on certain optimizations unless you have enough.  Four is sadly probably not enough for much of the performance benefit that they are working on.  Four is better than two (so on is better than off), but four is not where you see the real benefit from the new lightroom performance changes.


Ferguson,

How many cores are enough for LR 7.2?

Phil


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## Linwood Ferguson

PhilBurton said:


> Ferguson,
> 
> How many cores are enough for LR 7.2?
> 
> Phil


I am not aware that 7.2 changed the rules, I think 7.0 or 7.1 is when they put in the checks.  7.2 is vastly better at some things, however, so you benefit more there. 

I found 8 (4 x hyperthread) worked, and 4 (turn HT off) did not, so somewhere between 4 and 8.  I did not have a way to try 6 (which some may have with non-HT architectures).

Basically, as best I can tell, LR throws in a lot more parallelism in later versions, and it is more effective in each version, but they do not turn it on if they think you have too few cores to have your computer still perform adequately while they do a lot of parallel work.  

One quick way to tell if you have enough cores (at least to start this) is do a largish import, and if it starts building previews while it is still copying files, it has enough cores.  I do not know if there are lots of additional things that start at 8, 12, 16, etc. cores, but that seems to be a good, quick test of the basic minimum level.


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## Linwood Ferguson

Incidentally, the above mentioned test to see if you have enough cores to shave the parallelism performance stuff really kick in is in 7.1 (maybe in 7.0 I can't recall).  Here's what it looks like just doing an import if it's building in parallel, it shows two things, and the bottom line runs, completes (it does the first few) then runs again and finishes that set, and continually runs until all previews are built -- which may be pretty close to when the import finishes if you have a slow card reader.


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## Zenon

Ferguson said:


> As Hal mentions that likely means Hyper Threading is on. This is controlled in your bios, not in windows.  The normal default is on, as it makes systems "look" more substantial than otherwise.
> 
> In days past it was questionable whether HyperThreading was a good thing, but with LR 7.1 and soon to be released 7.2, HyperThreading is a good thing, as Adobe counts cores and does not turn on certain optimizations unless you have enough.  Four is sadly probably not enough for much of the performance benefit that they are working on.  Four is better than two (so on is better than off), but four is not where you see the real benefit from the new lightroom performance changes.



What do you mean by - on is better than off?


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## Linwood Ferguson

Zenon said:


> What do you mean by - on is better than off?


On systems where bios and processor support it, hyperthreading can be turned on or off.  In LR7 and above I suggest turning it on is better.  On is usually the default, so this generally means doing nothing.

In LR5, and I think most if not all of LR6, my testing showed Hyperthreading turned off to be slightly better.  That is normally the case when an application has limited parallelism, i.e. if it is doing only 1, 2, or 3 things at a time (for example), then a 4 core system running as 4 will run faster (off) than a 4 core system pretending to be 8 (which is what HyperThreading really is -- a hardware/software cooperation to pretend to be more cores than there are).   This presumes the application does the same thing regardless of number of cores, and one is measure which is better.

In LR7 something different happens -- LR decides what to do based on the number of cores, so it is not a question of whether 4 or pseudo-8 is better, but rather that as a side effect of turning on hyper-threading (if you have 4 real cores) you are also turning on lots of other performance enhancements. So definitely "On" is better now for 4 core systems for sure.

Now is on better for 8 core systems (that support it)?  I do not know, as then I think Adobe would have performance enhancements turned on at 8, and also for pseudo-16, and we would be back to measuring apples vs apples .  I do not have a 6 or 8 core system to test (and as mentioned I never tested 6 so do not know where the break point is).

By the way... I do not want to leave the impression that turning enhancements on or off is some elitist role, and they are penalizing small core systems needlessly -- the rationale appears to believe that if turned on for small core systems, it would consume the system enough it would otherwise hang, and you could not easily access it (e.g. to stop preview build or some such).  Did they get the breakpoint right?


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## David Gordon

Ferguson said:


> On systems where bios and processor support it, hyperthreading can be turned on or off.


Must be a PC thing, I don't think Mac users have the option. (Unless there's some kind of terminal command, but I’ve never heard of this.)


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## Hal P Anderson

David Gordon said:


> I don't think Mac users have the option.



It isn't an operating system command. It happens at a lower level than that. Linwood mentioned earlier that it's a BIOS command. On Windows (and probably on a Mac) you can hold down a special key while booting the system that brings up a screen that lets you modify how the hardware works. One of the things you can do there is to turn hyperthreading on and off.


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## Johan Elzenga

Hal P Anderson said:


> It isn't an operating system command. It happens at a lower level than that. Linwood mentioned earlier that it's a BIOS command. On Windows (and probably on a Mac) you can hold down a special key while booting the system that brings up a screen that lets you modify how the hardware works. One of the things you can do there is to turn hyperthreading on and off.


Macs don't have a BIOS. Macs boot using EFI. There is no equivalent to the BIOS settings on a PC. There are some things you can do at startup (Mac startup key combinations), but nothing like turning on/off hyperthreading.


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## Zenon

Thanks everyone.


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## Linwood Ferguson

JohanElzenga said:


> Macs don't have a BIOS. Macs boot using EFI. There is no equivalent to the BIOS settings on a PC. There are some things you can do at startup (Mac startup key combinations), but nothing like turning on/off hyperthreading.


On PC's with EFI you can set it there also.  I used the term "Bios" really to imply "whatever is in your hardware that starts it up". 

Some Mac's with intel chips do support it, and apparently (google is my friend) you can disable it, as described in this posting on stackexchange.  note I'm not suggesting you should disable it.   the posting is a bit old but I saw other references to the same program from mid-2017.

How to disable HyperThreading on Mac OS X Yosemite?

Note I can barely spell Mac so I know nothing at all about the program mentioned and whether this works, only that HyperThreading is innate in certain Intel CPU's, and Mac uses some of them, so yes, you have it.


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## Hal P Anderson

Thanks, Johan. An Intel-based computer without a BIOS. Who would have thought?


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## Zenon

Now I'm not so hyper about figuring it out.


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## Linwood Ferguson

Hal P Anderson said:


> Thanks, Johan. An Intel-based computer without a BIOS. Who would have thought?


I haven't had a (non-UEFI) bios in any computer for years, and I'm pure Windows/Intel.  

Heck, even my VM guests running in HyperV use UEFI. 

Time passes when you're out shooting.


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## Johan Elzenga

Ferguson said:


> On PC's with EFI you can set it there also.  I used the term "Bios" really to imply "whatever is in your hardware that starts it up".
> 
> Some Mac's with intel chips do support it, and apparently (google is my friend) you can disable it, as described in this posting on stackexchange.  note I'm not suggesting you should disable it.   the posting is a bit old but I saw other references to the same program from mid-2017.
> 
> How to disable HyperThreading on Mac OS X Yosemite?
> 
> Note I can barely spell Mac so I know nothing at all about the program mentioned and whether this works, only that HyperThreading is innate in certain Intel CPU's, and Mac uses some of them, so yes, you have it.


Not really. Did you read the last sentence in link? "*However, after restarting your Mac it will be enabled again.*". And MacOS X Yosemite is very old. XCode has changed a lot since then. It no longer contains all kinds of separate applications, it's one single package right now. So I doubt that the method in that link is still valid.


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## Linwood Ferguson

So then in current Mac OS there's no way to permanently disable hyper-threading?

I guess that's in keeping with Apple's "have it our way" philosophy in most things.


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## tspear

Hal P Anderson said:


> Thanks, Johan. An Intel-based computer without a BIOS. Who would have thought?



Actually, EFI is BIOS. Well BIOS on steroids. It abstracts a slightly higher level above the core BIOS hardware layer. In theory this will improve performance, and reduce driver and other issues commonly found in the OS. The idea is to provide a more common abstraction layer.

Tim


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## PhilBurton

JohanElzenga said:


> Macs don't have a BIOS. Macs boot using EFI. There is no equivalent to the BIOS settings on a PC. There are some things you can do at startup (Mac startup key combinations), but nothing like turning on/off hyperthreading.


No PC, not based on a modern motherboard, would use the old classic BIOS.  All modern designs utilize UEFI interface to control hardware.  However, the term "BIOS" lingers on.  The BIOS was invented, or at least popularized by IBM when the brought out their PC in 1981.

Phil


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## Johan Elzenga

Whatever. You guys are missing the point. The point is that -at least AFAIK- you can't disable hyperthreading on a Mac running the latest MacOS X version.


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## Linwood Ferguson

JohanElzenga said:


> Whatever. You guys are missing the point. The point is that -at least AFAIK- you can't disable hyperthreading on a Mac running the latest MacOS X version.


Yeah, I've been curious since this started, and there is tellingly little on the subject.  I've found a couple places where they say you can use "instruments" to disable it (whatever that is) but that it doesn't persist.

Michael Tsai - Blog  -  Bug in Skylake and Kaby Lake Hyper-threadingMichael Tsai - Blog  -  Bug in Skylake and Kaby Lake Hyper-threading

I'm not sure if that works or not, but it has a recent date.  It concerns a bug related to HyperThreading in specific CPU's.  But there's very little discussion about HyperThreading in Mac's, I guess, because Apple turns it on and makes it stay on for either all, or all but a persistent few who dig deeply.

Which again... for later versions of Lightroom, is probably the best bet.  And on old versions the downside was very, very minor of being on.


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## Johan Elzenga

Apparently 'Instruments' was one of the many apps that used to be part of XCode (Apple's programming environment). In the past, XCode was a folder that contained lots of individual apps, and templates and other stuff. The latest version of XCode isn't like that anymore. It's a single, huge application (11 GB) now. Because Mac applications are 'packages' (folders that behave like they are files), the 'Instruments' app may still be in the package somewhere, but you sure won't find it using Spotlight.

UPDATE: I peeked inside the XCode package and 'Instruments' is indeed still in there. So people who know how to do this may still use 'Instruments', but apparently that will only turn off hyperthreading until a restart.


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