Known Participant

Question

LrC 15.3.1 Export Performance Issues on Mac Studio M1 Max – High CPU, Low GPU/Render Utilization

Forum|Forum|24 days ago
June 4, 2026
5 replies
67 views

Hi everyone,
I'm experiencing severe export slowdowns in the latest Lightroom Classic 15.3.1 on my Mac Studio (M1 Max, 24-core GPU, macOS Tahoe). Exporting 500 high-res RAW images to maximum quality JPEGs takes way longer than it used to, and my hardware is not being utilized properly.
During the export process:
•   CPU usage is pinned at nearly 100% (Full Red).
•   GPU Utilization sits around 60-70%.
•   GPU Render and Tiler utilization drops down to just 5%.
•   ANE (Neural Engine) utilization stays at 0%.
It seems like a massive I/O or processing bottleneck where the CPU is completely choked, while the GPU is just sitting idle waiting for data.
What I have already tried (which only partially helped or didn't fix the underlying bug):
   1.   Camera Raw GPU Config Fix: Checked the Camera Raw GPU Config.txt file and noticed crs:gpu_preferred_system="" was completely blank. Cleared the entire GPU cache folder and forced LrC to re-test the hardware.
   2.   Hard Reset: Performed a full preference hard reset using the Shift+Option+Command shortcut on startup and cleared all Lightroom cache folders. This improved the speed slightly (now around 2-5 seconds per frame), but the hardware imbalance remains (100% CPU vs 5% GPU Render).
   3.   Lightroom Performance Settings: GPU acceleration is explicitly set to Custom with both "Use GPU for image processing" and "Use GPU for Export" checked.
   4.   Export Settings: I am not using any Output Sharpening, Watermarks, or custom File Naming sequences that typically slow down exports. My Camera Raw cache is cleared and set to 100GB.
Why is the single-batch export engine in v15.3.1 so poorly optimized for Apple Silicon compared to older versions where the GPU actually did the heavy lifting and the CPU stayed quiet? Is there any other hidden config file or setting to force proper GPU/ANE load distribution?
Thanks!

Lightroom Classic version: 15.3.1 [ 202605261338-e36f8566 ]
License: Creative Cloud
Language setting: lv-LV
Operating system: Mac OS 26
Version: 26.5.1 [25F80]
Application architecture: arm64
Logical processor count: 10
Processor speed: NA
SqLite Version: 3.36.0
Adobe GSDK Version: 1.4.0.213

Built-in memory: 32 768,0 MB
Dedicated GPU memory used by Lightroom: 587,8MB / 25 559,0MB (2%)
Real memory available to Lightroom: 32 768,0 MB
Real memory used by Lightroom: 5 342,4 MB (16,3%)
Virtual memory used by Lightroom: 449 898,2 MB
Memory cache size: 1 188,4MB
Internal Camera Raw version: 18.3 [ 2530 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2
Camera Raw virtual memory: 1690MB / 16383MB (10%)
Camera Raw real memory: 3344MB / 32768MB (10%)

Cache1:
NT- RAM:0,0MB, VRAM:0,0MB, Combined:0,0MB

Cache2:
m:1 188,4MB, n:0,0MB

U-main: 151,0MB

Standard Preview Size: 5120 pixels
Displays: 1) 5120x2880, 2) 2560x1440, 3) 2560x1440

Graphics Processor Info:
Metal: Apple M1 Max
Init State: GPU for Export supported by default
User Preference: Auto
Enable HDR in Library: OFF
GPU for Preview Generation: Auto (S5_24)

Application folder: /Applications/Adobe Lightroom Classic
Library Path: /Volumes/4TB-LEXAR/2026/2026.lrcat
Settings Folder: /Users/kasparssilins/Library/Application Support/Adobe/Lightroom

Installed Plugins:
1) AdobeStock
2) Aperty
3) Aperture/iPhoto Importer Plug-in
4) Aurora HDR
5) Calibrite Camera Calibration
6) ColorChecker Camera Calibration
7) Export to Photomatix Pro
8) FilterPixel-Edits
9) Flickr
10) Imagen plugin
11) Impossible Things
12) Impossible Things Help
13) Lightpanel 2025
14) Logi Plugin
15) Luminar AI
16) Luminar Neo
17) Neurapix
18) ON1 Photo RAW 2025
19) Peakto Opener
20) Radiant Photo
21) Radiant Photo 2
22) Reblum
23) Retouch4me Arams
24) Topaz Photo (Studio)
25) Topaz Photo AI

Config.lua flags:

K

kgdizainslvAuthor

Known Participant

It has nothing to do with the Lexar drive. It's a Thunderbolt 4 SSD with speeds over 2500 MB/s. Plus, the exact same thing happens on the MacBook where the photos are stored directly on the built-in internal drive.

KR Seals

Community Expert

What type of drive is 4TB-LEXAR? How is it connected to the Mac Studio?
Where are the files to be exported located? What type and speed is that drive?

Ken Seals - Nikon Z 9, Z 8, 14mm-800mm. Computer Win 11 Pro, I7-14700K, 64GB, RTX3070TI. Travel machine: 2021 MacBook Pro M1 MAX 64GB. All Adobe apps.

Anshul_Saini

Community Manager

Hi @jmsauder @bellevue scott @kgdizainslv,

Thanks for sharing your observations. Since the original post, we’ve released Lightroom Classic 15.4.1. Could you all please update to the latest version and let us know whether you’re still seeing the same behavior?

If the issue persists after updating, it would help if each of you could share:

• Your latest System Info (Help > System Info > Copy & Paste)

• A short screen recording showing the slowdown (for example, during export, culling in Library, or other affected workflows)

A couple of additional questions:

• Does the slowdown occur only during exports, or do you also notice it while browsing/editing photos?

• Approximately how many images are you exporting, and what file type are they (RAW, JPEG, etc.)?

• Does the issue occur with a specific catalog, or can you reproduce it in a new test catalog with a small number of images?

The more we can compare the behavior across different systems, the easier it will be to determine whether this is a broader performance regression or something specific to certain workflows or catalogs.

Best,
Anshul Saini

bellevue scott

Inspiring

I rolled back to 13.5.1 because I do tethered capture with the Fuji GFX100. Since Adobe LRC added support for the GFX100 after that, it’s unusable for us because LRC takes over the native Fuji capture SW, which would be fine if it worked, but all the settings of the camera are gone and we can’t use it. So we’re on 13.5.1 for now, or forever. Please understand it’s the ONE thing we use it for when photographing artwork for reproduction. Tethered capture, export with custom profiles, and then the images move to PS. And if that part breaks, then we’ll move to another program for tethered capture raw processing.

bellevue scott

Inspiring

I am using LRC 13.5.1 on a machine in my camera room that I use for tethered capture. I’ve left it at 13.5.1 because later versions of LRC have an issue after implementing support for the Fuji Medium Format cameras that make tethering capture unusable.

I can confer that exports are extremely slow. I will often export 1-10 images at a time during tethered capture and a single image can take up to a minute sometimes. You also can’t multitask in LRC while doing an export, so I sit and wait and wait for it. It’s a real thing. You’re not imagining it.

jmsauder

Participant

LR Classic 15.3.1 is using 100% of the CPU on my Mac Mini constantly, even when I’m not doing anything at all. The application is almost unusable. Just culling images, stepping through them one-by-one in Library view, has so much lag that it’s unbearable to use.

jmsauder

Participant

I should mention I’m using a Mac Mini M4 Pro with 48 GB memory, running Tahoe. I only noticed a slowdown after the last LR Classic update.

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