Poor performance in the Develop module on retina iMac

[FredT]

All of the Develop module operation are extremely slow on my retina iMac.  This machine has the 4.0 GHz processor and upgraded GPU.  It should be very fast, and in fact for operations such as import, export, and preview creation it is.  But for Develop module functions it is much slower than my Mac Mini and my wife's Macbook Air.  When moving adjustment sliders, there is a delay of a second or more before the effect is seen on screen.  The same operation on the other computers is nearly instantaneous.  I am running version 5.6, but I went back and tried it with version 4.4 as well with the same result.  Can anyone give me advice on how to proceed?  I've contacted Apple support, but they are puzzled and suggest contacting Adobe.  I haven't found a way to do that directly.  The support pages keep taking me to the user forums.  Thanks.

[KarlGohl]

Develop's interactive response is highly dependent on the number of pixels in the image part of the window.  A 13" MacBook Air display has about 1.3 million pixels.  The 5K iMac display has about 14 million pixels, so you need 10 times the processor power, 10 times the memory bandwidth, etc to get equal responsiveness.  If you make your LR window 1/3 the width and 1/3 the height of the iMac's display, it will have about the same number of pixels as the MB Air.  Try making the window that size and see what kind of performance you get.  I think it will be much better, confirming that display size is the main culprit.

You can try setting other screen resolutions in the Displays pane in System Prefs.  (Hold Option while clicking the Scaled radio button to see all available sizes.)  I'm not that up on how scaling is handled for "retina" displays.  It could be that since LR is "retina aware", it will see the full resolution of the image part of the window even at the other resolutions.  If so, it will still display the same number of pixels for the image (and just the controls will be bigger) so performance won't improve much.

Currently we're in a Catch 22 situation for 5K displays: An iMac can have a 5K display because the connection is internal, but iMacs are limited to 4 core non-server CPUs.
Mac Pros can have more CPU power, but their Display Port 1.2 connectors don't have enough bandwidth to drive a 5K display.  Anyone intending to use LR on a 5K iMac should get the fastest CPU option available.  (I hope you did that.)

It could be that the best way for you to use LR is to keep the size of the image portion of the window small enough to get adequate performance and occasionally use Full Screen mode to view the image in 5K glory.

[Geraldo Garcia]

I feared that from the announcement... no way an iMac would have the computing power to make use of such resolution in lightroom. Sad to hear that it is true.
In other words, Apple gives you a 5K display but not the power to use it properly. It is like having racing tires on a minivan.

[FredT]

Develop's interactive response is highly dependent on the number of pixels in the image part of the window.  A 13" MacBook Air display has about 1.3 million pixels.  The 5K iMac display has about 14 million pixels, so you need 10 times the processor power, 10 times the memory bandwidth, etc to get equal responsiveness.  If you make your LR window 1/3 the width and 1/3 the height of the iMac's display, it will have about the same number of pixels as the MB Air.  Try making the window that size and see what kind of performance you get.  I think it will be much better, confirming that display size is the main culprit.

You can try setting other screen resolutions in the Displays pane in System Prefs.  (Hold Option while clicking the Scaled radio button to see all available sizes.)  I'm not that up on how scaling is handled for "retina" displays.  It could be that since LR is "retina aware", it will see the full resolution of the image part of the window even at the other resolutions.  If so, it will still display the same number of pixels for the image (and just the controls will be bigger) so performance won't improve much.

Currently we're in a Catch 22 situation for 5K displays: An iMac can have a 5K display because the connection is internal, but iMacs are limited to 4 core non-server CPUs.
Mac Pros can have more CPU power, but their Display Port 1.2 connectors don't have enough bandwidth to drive a 5K display.  Anyone intending to use LR on a 5K iMac should get the fastest CPU option available.  (I hope you did that.)

It could be that the best way for you to use LR is to keep the size of the image portion of the window small enough to get adequate performance and occasionally use Full Screen mode to view the image in 5K glory.

Thanks Karl, I figured that I'd get a good explanation here.  You are right on all counts.  I first tried making the Lightroom window smaller, and that smoothed things out nicely.  I also tried running in 2560x1440 low resolution mode, which essentially emulates a non-retina 2560x1440 display, and again controls operate smoothly.  For now I'll try to get used to it.  It's not horrible for most of the kinds of adjustments I normally make.

[Wayne Fox]

Thanks Karl, I figured that I'd get a good explanation here.  You are right on all counts.  I first tried making the Lightroom window smaller, and that smoothed things out nicely.  I also tried running in 2560x1440 low resolution mode, which essentially emulates a non-retina 2560x1440 display, and again controls operate smoothly.  For now I'll try to get used to it.  It's not horrible for most of the kinds of adjustments I normally make.

Kevin didn’t seem to have an issue like this, although he’s probably just getting around to working with the machine more.

What resolution did you have the iMac setup when you were having issues?  Even though you are emulating 2560x1440, LR is retina aware, and utilizes the full resolution of the display in the image areas of the program, so if the iMac is choking on the massive amount of pixels in the image area,  changing to an emulated resolution shouldn’t make much of a difference.  Emulating a lower working resolution is one of the basic concepts behind the design, it removes the need for using a “native” resolution. 

[StuartOnline]

Terry White did a pretty good comparison between the new iMac 5K and the Mac Pro:
http://terrywhite.com/photographers-imac-retina-5k-vs-mac-pro/

I though it was pretty interesting the results on how well the iMac 5K performs.

Stu

[Geraldo Garcia]

Terry White did a pretty good comparison between the new iMac 5K and the Mac Pro:
I though it was pretty interesting the results on how well the iMac 5K performs.

Unfortunately he focused on measuring the speed of tasks performed by the computers. He did not touch the subject of how fast/promptly some softwares behave when you try to take full advantage of the 5K display you paid for. Lightroom's interface, for instance, always suffered with high resolutions on not so fast computers.
Sure the new iMac is not weak on processing power, but is it strong enough to handle his own display?

[CatOne]

Unfortunately he focused on measuring the speed of tasks performed by the computers. He did not touch the subject of how fast/promptly some softwares behave when you try to take full advantage of the 5K display you paid for. Lightroom's interface, for instance, always suffered with high resolutions on not so fast computers.
Sure the new iMac is not weak on processing power, but is it strong enough to handle his own display?

Do we also know this is an iMac problem versus a Lightroom problem? How do Aperture or C1 perform under these same circumstances? I mean the Mac can draw the entire screen at 60 FPS.

[FredT]

What resolution did you have the iMac setup when you were having issues?  Even though you are emulating 2560x1440, LR is retina aware, and utilizes the full resolution of the display in the image areas of the program, so if the iMac is choking on the massive amount of pixels in the image area,  changing to an emulated resolution shouldn’t make much of a difference.  Emulating a lower working resolution is one of the basic concepts behind the design, it removes the need for using a “native” resolution. 

I have the resolution set to "Best for retina", which is the 2560x1440 high res mode.  At this resolution, Lightroom has to work with a very large number of pixels.  I have three tests that I think demonstrate that it is in fact this large number of pixels that is affecting performance:

1. If I zoom in to 2:1, adjustments smooth out.

2. If I resize the the Lightroom window to fill about 1/3 of the screen, adjustments likewise get much smoother.

3. If I put the screen in 2560x1440 low resolution mode, which turns it essentially into a standard 27-inch iMac display, again adjustments are smooth.

In all of those cases Lightroom is working with fewer pixels and performance improves.  Having said all of that, I'm now OK with performance.  Whether it's something I did when I was trying various things to work through the issue, or perhaps just a matter of me adjusting to how it behaves, in practice the only place that I see really obvious jerkiness is with the graduated filter and transformations.  I rarely use those.  And there's some funkiness with cropping, but I think that can be fixed by Adobe.

[KarlGohl]

I'm not clear about what you mean by the "2560x1440 high res" versus "2560x1440 low resolution mode".  When I played with the display settings on a 5K iMac at an Apple store, I didn't see any such distinction.  Can you explain how you choose one versus the other?

[FredT]

I'm not clear about what you mean by the "2560x1440 high res" versus "2560x1440 low resolution mode".  When I played with the display settings on a 5K iMac at an Apple store, I didn't see any such distinction.  Can you explain how you choose one versus the other?

Sure.  In the display preference, if you hold down the Option key while clicking on "scaled", you are presented with a list of eight resolutions ranging from 1280x720 to 5120x2880.  If you then click on the "Show low resolution modes", the list expands to include low resolution versions of all but the 5120x2880 one.

[Wayne Fox]

The option key trick must be unique to the iMac because it doesn’t work that way on a retina macbook pro.  Apple doesn’t mention that in the support document.

You can force any individual app to low resolution mode when using any retina Mac by doing a get info on the application, and then checking the Open in Low Resolution checkbox.

edit.  Played with a 5K iMac today, the option click thing is pretty cool.  It allows you to pick any resolution including the full native resolution, so no need for switch resx to do that. things are definitely tiny at full rez, but sharp and crisp.  If you have good eyes and like sitting close to the screen could even use it.

Most of the low resolution modes looked soft, even 1920x1440, which should scale down very well.  Not sure why.  Friend is thinking of one so we’re headed to the dealer next week to install LR and see how much of a lag issue there is.

[ryanjw]

Thank you, this solved the problem for me. The 27 Retina iMac simply isn't powerful enough to support Lightroom in high-res mode. Luckily the degradation in picture quality is not drastic. 

[Wayne Fox]

Thank you, this solved the problem for me. The 27 Retina iMac simply isn't powerful enough to support Lightroom in high-res mode. Luckily the degradation in picture quality is not drastic. 

Interesting.  A good friend who shoots 36mp nikon just set up one, and is having no performance issues at all,  in fact noticeably faster than his macbook pro.

[FredT]

Interesting.  A good friend who shoots 36mp nikon just set up one, and is having no performance issues at all,  in fact noticeably faster than his macbook pro.

I find it faster for imports, exports, building previews, etc.  It's only when I get into the develop module that things slow down.

[John Caldwell]

I did not have the impression that most iMac users were having the OP's experience in Develop when running in high-resolution mode. Is this, in fact, the consensus experience?

John Caldwell

[John S C]

Interesting.  A good friend who shoots 36mp nikon just set up one, and is having no performance issues at all,  in fact noticeably faster than his macbook pro.

Does this include not having the same problems as the OP

[CatOne]

I haven't noticed performance that's worse on this iMac than it was on the 2010 12-core Mac Pro that it replaced. It seems OK to me. I wouldn't say it's blindingly fast, but it's pretty quick.

[Wayne Fox]

Does this include not having the same problems as the OP

yes.  he says the develop module isn't a problem at all.

[jarnoh]

I have a dual-core retina Macbook Pro 13", and also I feel that LR is a bit sluggish compared to my old 15" quad-core non-retina (which is only about 15% faster according to benchmarks, even though it has twice the core count).

My solution has been running Lightroom app itself in scaled mode by going to Lightroom.app's Info panel (in Finder, File -> Get Info) and checking "Open in Low Resolution".  It doesn't make miracles, but every tiny bit helps, and I don't have to run whole computer in scaled resolution.