4K Monitor Setup | Sluggish Performance

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@Manas2292 wrote:

I recenlty connected a 27" 4K monitor to my macbook pro (mid-2015 series). Its near impossible to use Lightroom on the 4K monitor unless I scale the resolution on the monitor to 1080P. I am trying to understand the reasoning behind this. 

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If it is a performance issue, it could be related to this:

• The built-in display is 2880 𝗑 1800 pixels. That’s 5.2 megapixels, and the internal graphics are tuned for that. 
• A 4K display like the LG 27UL550 is 3840 𝗑 2160 pixels. That’s 8.3 megapixels. You can see right away that increases the load on the graphics hardware by 60%, compared to using the internal display. It will not be surprising for performance to seem slower.

Another question: When you run the external 4K display, is the MacBook Pro lid open or closed? Because when it’s open, now the weak integrated graphics have to run the total number of pixels of both displays. So we get:

Internal display only: 5.2 megapixels

External 4K display only: 8.3 megapixels, 60% more pixels to update.

Both displays: 13.5 megapixels, 160% more pixels to update compared to the internal display only.

I agree with Abambo and others that it is not an HDMI/DisplayPort issue, it is about the weak Intel integrated graphics getting bogged down by being asked to update a lot more pixels at once, combined with Lightroom asking the CPU to recalculate more pixels at once (from raw to RGB plus adjustments) with every edit you make.

Another possible factor is that if you have the 13" MacBook Pro (likely, if it has only integrated graphics),  then the CPU is just dual-core. That would also work against it, since many computers today that work well with 4K have a CPU with at least 4 cores, to help process all that additional data.

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@Manas2292 wrote:

I'm using a high speed HDMI cable as well - will Lightroom never work smoothly on a 4K monitor? I am planning on purchasing a mac - mini in the near future

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Lightroom 6 will never be updated again. But Lightroom Classic 7 through 10 progressed through a series of improvements to GPU acceleration which are supposed to have improved things greatly on 4K and up displays…if the graphics hardware is powerful enough. On current Macs it is, on a 2015 MacBook Pro (now 6 years old) it is not.

A new M1 Mac mini should perform much better on a 4K display for several reasons:

• The M1 Mac mini benefits from having an 8-core CPU and an 8-core GPU using the Unified Memory Architecture, which should perform better than Intel Integrated Graphics in general, and definitely much better than what is in a 2015 MacBook Pro. Just make sure to buy it with 16GB RAM.
• You can’t run Lightroom 6 on Apple Silicon, so you will be forced to update to Lightroom Classic 10 or later, which is a good thing because it will include all those recent improvements to GPU acceleration and is also optimized for Apple Silicon performance. 

One workaround that some people use for older computers running 4K displays is to reduce the size of the Lightroom application window, so that the Develop module needs to update fewer pixels with each edit. Another tactic is to reduce the Standard Preview size (in Catalog Settings, File Handling tab).

Displayport or HDMI is not the problem. The problem is always to shuffle the data around. The ports and cables will support their resolution at the given refresh frequency. That is primary not a speed but a bandwith problem.

And, what is your exact nake/model of computer?

Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.

Sample below as of 7/1/2021

Lightroom Classic version: 10.3 [ 202105281559-8dc50eb4 ]
License: Creative Cloud
Language setting: en
Operating system: Windows 10 - Business Edition
Version: 10.0.19043
Application architecture: x64
System architecture: x64
Logical processor count: 8
Processor speed: 4.0GHz
SqLite Version: 3.34.0
Built-in memory: 16317.1 MB
Real memory available to Lightroom: 16317.1 MB
Real memory used by Lightroom: 1302.8 MB (7.9%)
Virtual memory used by Lightroom: 1586.9 MB
GDI objects count: 746
USER objects count: 2288
Process handles count: 1909
Memory cache size: 252.3MB
Internal Camera Raw version: 13.3 [ 807 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 299MB / 8158MB (3%)
Camera Raw real memory: 303MB / 16317MB (1%)
System DPI setting: 96 DPI (high DPI mode)
Desktop composition enabled: Yes
Displays: 1) 2560x1440
Input types: Multitouch: No, Integrated touch: No, Integrated pen: Yes, External touch: No, External pen: Yes, Keyboard: No
Graphics Processor Info: 
DirectX: NVIDIA GeForce GTX 1070 Ti (27.21.14.6089)

Application folder: C:\Program Files\Adobe\Adobe Lightroom Classic
Library Path: F:\Files\Pictures\Vacations and Day Trips\Photo Trips\24 Photo Trip September 2019\24 Photo Trip September 2019-v10.lrcat
Settings Folder: C:\Users\goldi\AppData\Roaming\Adobe\Lightroom

Installed Plugins: 
1) Aurora HDR
2) ColorChecker Camera Calibration
3) DxO PhotoLab 3
4) DxO PhotoLab 3 Importer

What GPU do you have?

What version NUMBER of Lightroom or Lightroom Classic do you have? (We need the version NUMBER and not words like "current" or "up-to-date")

I've been using it on a 5K retina for 5+ years. You have to remember that your preview size is now essentially 1:1 as Lightroom generates these to use if the screen is more than half the resolution of the files. These take longer to load. Other than that, I've not noticed any UI related issues with the higher resolution. Is there something specific, or is it about the image loading?

The Mini would certainly be faster, though it may be due an upgrade shortly with college restarting. Potentially this month or next.