# Does an i7 processor make much speed difference?



## CloudyBright (May 12, 2014)

Greetings,

As you might know, the Intel i7 processor is capable of "hyperthreading" and Lightroom is one of the programs capable of using the hyperthreading technology.

That said, has anyone used Lightroom on both an i7 processor based machine and an i5, or i3 based machine and seen much, if any, difference?

And is it worth the extra month for an i7 processor?


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## clee01l (May 12, 2014)

Even the Dual core i5 has hyperthreading. Here ia a link that explains the differences:
http://www.pcmag.com/article2/0,2817,2404675,00.asp
Your i5 is going to max out a 4 cores while the i7 can be obtained with more than 4 true cores. I think the most important feature to look for is the number of true cores. LR can make use of all of them.

I have a dual core i7 and quad core i5 Both run LR well and the only limitation I can find is on the dual core i7 which is more limited by 8GB of RAM than number of processors.


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## CloudyBright (May 13, 2014)

Hummmm. . .   "i5 CPUs do not support Hyperthreading" . . .?
My useage typically will be to run LR while running Expression Web, XAMMP server software (apache and MySql, Corel PhotoPaint X2, a browser and possibly email in the background.

So. . .sorry I didn't mention that the first time. . .
I typically run at least three applications and often five applications while working on a project.
All of which are somewhat demanding.


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## clee01l (May 13, 2014)

CloudyBright said:


> Hummmm. . .   "i5 CPUs do not support Hyperthreading" . . .?


That's right.  Both links do not disgree. Quad Core i5 CPUs do not have hyperthreading.  Dual Core i5 CPUs do but are limited to only 4 virtual cores.   
Do not confuse hyper threading with multithreading.  Each CPU can process only one thread at a time.  In Hyperthreading that does not really change. Hyperthreading stages two threads for the same core creating a virtual core such that if one thread takes "1x" time to  process an instruction, the a hyper thread can process 2 instructions in the same core in slightly longer than "1x" time

Many apps can be open and each can own a number of threads. These will still be processed serially for each core and the CPU will switch between them as necessary and in turn.  Each App will get about 2GB of address space some of that gets assigned to the pagefile if there is not enough available RAM.  Most of the apps open will be in an idle state waiting for you to press a key or click your mouse.


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## CrabbyGuy (May 13, 2014)

I am shopping for the processor to build a new motherboard and had intended to get an i5 Haswell.  (Running LR is my most demanding application.  I will normally run just one or two applications with it.)  I found this:  *http://www.cpu-world.com/Compare/513/Intel_Core_i5_i5-4570_vs_Intel_Core_i5_i5-4570T.html*  comparison and am now confused.  I hope you can help me.  The i5-4570T has less "stuff" on the chip but does support hyperthreading.  Other similar i5 chips have more stuff on the chip, use more power (heat is a consideration for me), but do not support hyperthreading.  Price is similar.

Is the i5-4570T the right processor for my needs (running LR primarily)?


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## Jim Wilde (May 13, 2014)

If your desire for hyper-threading is specifically for Lightroom use, then I really wouldn't be overly concerned about buying a CPU which doesn't support it. The two main areas of Lightroom which are highly CPU-intensive are rendering previews and exporting, and in all the tests I've done over the years there was a noticeable change from LR4.3 onwards. Prior to that version, running with hyper-threading enabled was slightly quicker than with it disabled (and "slightly" means just that....rendering 100 1:1 previews for instance took 391 seconds with H/T disabled, 380 seconds with H/T enabled). But since LR4.3, running those tasks with H/T enabled has been consistently slower than with H/T disabled (386 seconds with no H/T, 409 seconds with H/T, same 1:1 previews on LR4.3).

Since then, that story has been repeated, though the gap has narrowed a little, For example, running the same preview test under LR5.4, the timings are: 364 seconds without H/T, 378 seconds with H/T.

That's not to say that the trend won't be reversed in future versions of LR, though I very much suspect that there'll not be a huge performance advantage when using H/T in Lightroom.


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## CrabbyGuy (May 15, 2014)

Jim,

I very much appreciate your response; it saved me from spending my money on the wrong processor, at least for LR 5.  I have subsequently looked for other postings on this topic and they present nearly identical results to yours.  It appears that the fastest overall performance of a processor is the best for the current version of LR.

While on the topic of building a new PC to run LR, I would like to solicit your view on the importance of having an SSD to improve LR performance.  In my very, very old PC I put a 15,000 RPM HDD for the LR cache and it appeared to make a difference.  In any case, what LR files should be directed to an SSD or should it just be skipped?

Again, thanks.


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## Jim Wilde (May 15, 2014)

Regarding the SSD, have a read of this article by Ian Lyons. His conclusion is that the best use of an SSD would be for housing the LR catalog, which is something I did last year (installed two SSDs, one for the system drive, one for my Lightroom catalogs) and obviously overall system performance is much snappier. I wouldn't say I saw a huge improvement in LR performance, primarily because it was already pretty good, but I'm sure there has been.

Regarding the ACR Cache, some folks have suggested that putting that on a SSD gets you the best bang for the buck, but I'm personally not that convinced. Key to the decision-making here is understanding how Lightroom operates "under the covers", particularly in respect of the various preview caches. For example, if a Smart Preview exists for a particular file then the ACR cache entry for that file is never used....and even when an ACR cache entry IS used, it's now a quite small file to read, so there's much less of an SSD advantage.

However, it's relatively easy to try different combinations of catalog and cache location, so if you do get an SSD you can try to find the best use of it. Personally, if I was only getting one I'd use it for the system drive first, though I'd maybe make sure it was big enough to house catalog and library previews as well.


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## MarkNicholas (May 16, 2014)

I'm no computer expert, but one thing I have learned over the years is that there is no single component of the computer that will magically speed things up but it does take just one slow component to slow everything down. Its only as fast as its slowest link.

When I upgraded my PC and installed LR4.xx I was blown away at the speed. But I quickly got used to it and when I installed LR5.xx I noticed a definite sluggishness compared to LR4.xx. But once again I have got used to it.


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## sdchew (May 22, 2014)

I upgraded from an old Core 2 Duo to a i7 extreme and I have a duo core i5 laptop. I find the extra cores only help when you are exporting photos. The extra cores really allows you to export large amount of photos while not crippling your machine 

Most if the time the i7 is operating idle. The i5 operates quite nicely in the develop module.


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## CrabbyGuy (May 22, 2014)

*I am learning quite a bit in this thread regarding running LR 5*



sdchew said:


> I upgraded from an old Core 2 Duo to a i7 extreme and I have a duo core i5 laptop. I find the extra cores only help when you are exporting photos. The extra cores really allows you to export large amount of photos while not crippling your machine
> 
> Most if the time the i7 is operating idle. The i5 operates quite nicely in the develop module.



I had started out believing that getting a processor that had hyperthreading capability would help me run LR 5.4 faster on a Windows PC.  Then (see other entries) I learned that hyperthreading would at best speed things up a very small amount and could even slow things down by a similar small amount.

Now I see that an i7 is more processor than is useful in practice for LR 5 and that an i5 processor has capability that is helpful mainly in the develop mode!

I am running LR 5.4 at the moment on a first-gen.-i3 Lenovo laptop with 4GB of RAM (the machine is four or five years old) and I entirely agree that LR 5 is far slower than LR 4, particularly in the develop mode.  I do have two questions:

1. Is the very old machine I am currently using so slow on LR 5 because of (a) a very slow processor, (b) a small amount of RAM by current standards, or (c) both?

2. Anyone have a guess about LR 6 and after in terms of what sort of PC should be built up today?  Is 8GB of RAM enough for LR 5, leaving room for 16GB down the road?

Many thanks to all for my education!


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## Jim Wilde (May 22, 2014)

I disagree that exports is the only place to benefit from a fast CPU. Exporting involves full raw conversion in order to render the export into the requested format (while obviously including any develop edits), then writing the rendered file to disk. Apart from the disk write at the end of the process (which is a very small fraction of the overall procedure), rendering 1:1 previews and loading images into Develop both need to do the same raw conversion and preview rendering, and so should exhibit similar CPU utilisation as exporting. That's certainly how it works (and has worked through all Lightroom versions) on my systems.

I also don't agree that "LR5 is far slower than LR4, particularly in the develop mode", that's not my experience and is not a general theme in the community (though with every new major release there are typically some who suffer worse performance). There was an article last year at the SLR Lounge which claimed that LR5 was slower than LR4 in many areas, and as that was not what I was seeing I ran some tests of my own and documented them here, if you get bored you can read the whole article. As you'll see, LR5 performance on my system matches and often exceeds LR4.

I'm running a four-year old system with a first generation i7 and 12gb of RAM.....and many of the later i5 processors will blow my i7 away, so I have no doubt that a modern i5 with at least 8gb of RAM (but 16gb would be better) *should *run Lightroom very well. As far LR6, who knows? I'm in the "starting to think about a new system" mode at the moment and if I was buying today I'd go for the fastest i7 four-core processor, i.e. the i7-4770k (too many reports of the 6-core users having performance trouble, but I don't know if that is simply because expectations aren't realised on such a powerful system). I'd also install at least 16gb RAM, though I'd probably save up a bit more and go for 32gb, and I'd probably keep my existing set of hard drives (2 x SSD and 3 x 7200rpm spinning disks).


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## CloudyBright (May 22, 2014)

Hi. me again.
I ended up buying a new machine with the i5-4440 chip.  And 12 gigs memory.  And it is faster than my now older i7 Dell XPS laptop.
The new machine, a Dell machine, had some Dell "bloatware", trial Office and some other stuff which I removed.  It help speed up the machine.
So I went back to the laptop and removed some of the Dell software and was able to also speed up that machine (achieving a higher performance rating using the Win 7 "performance" tools in the Control Panel.

I don't spend my day at the machine - and so do not need speed beyond my thinking abilities.


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