Lightroom Classic 15.5.1: Progressive physical-memory accumulation during Develop navigation with GPU acceleration enabled; memory remains retained while idle

I am seeing very substantial progressive memory growth in Lightroom Classic 15.5.1 on Windows 10 with 64 GB RAM.

Using Microsoft Process Explorer, I observed Lightroom.exe Private Bytes increasing during an ordinary Lightroom session approximately as follows:

6 GB → 9 GB → 15.5 GB → 33.9 GB

At one point Lightroom was using approximately 78% CPU, although later CPU dropped to about 5% while Private Bytes remained above 30 GB.

I initially suspected GPU acceleration because Lightroom started this morning with the GPU disabled. However, I restarted Lightroom with Use Graphics Processor explicitly set to OFF and the progressive memory growth still occurred.

I also closed ACDSee Ultimate 2027, which I had recently installed, and restarted Lightroom with ACDSee not running. Lightroom's Private Bytes still climbed rapidly, reaching approximately 10 GB shortly after launch. This therefore does not appear to require ACDSee to be running.

Process Explorer also showed substantial disk-read activity during one episode. Lightroom had its preview database (previews.db and root-pixels.db) open on my dedicated Lightroom preview SSD.

When Lightroom reached approximately 33.9 GB Private Bytes, its Working Set was approximately 9 GB. Closing Lightroom normally immediately released the allocated memory and Lightroom.exe terminated normally.

System:
Windows 10 Pro 22H2
Intel Core i9-10900
64 GB RAM
NVIDIA RTX 2060 6 GB
Lightroom Classic 15.5.1

I can provide further Process Explorer measurements/screenshots or run specific tests if useful.

System info: 

Lightroom Classic version: 15.5.1 [ 202608131348-cab7eed5 ]
License: Creative Cloud
Language setting: en
Operating system: Windows 10 - Business Edition
Version: 10.0.19045
Application architecture: x64
System architecture: x64
Logical processor count: 20
Processor speed: 2.8GHz
SqLite Version: 3.36.0
Adobe GSDK Version: 1.4.0.213

CPU Utilisation: 8.0%
Power Source: Plugged In
Built-in memory: 65452.7 MB
Dedicated GPU memory used by Lightroom: 729.9MB / 5945.0MB (12%)
Real memory available to Lightroom: 65452.7 MB
Real memory used by Lightroom: 7909.9 MB (12.0%)
Virtual memory used by Lightroom: 18187.6 MB
GDI objects count: 946
USER objects count: 3868
Process handles count: 3032
Memory cache size: 31.6MB
Internal Camera Raw version: 18.5.1 [ 2687 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 58MB / 32726MB (0%)
Camera Raw real memory: 61MB / 65452MB (0%)

Cache1: 
NT- RAM:0.0MB, VRAM:0.0MB, Combined:0.0MB

Cache2: 
m:31.6MB, n:0.0MB

U-main: 89.0MB

System DPI setting: 144 DPI (high DPI mode)
Desktop composition enabled: Yes
Standard Preview Size: 3840 pixels
Displays: 1) 3840x2160
Input types: Multitouch: No, Integrated touch: No, Integrated pen: No, External touch: No, External pen: No, Keyboard: No

Graphics Processor Info: 
DirectX: NVIDIA GeForce RTX 2060 (32.0.16.1062)
Init State: GPU for Image Processing supported by default
User Preference: Off
Enable HDR in Library: OFF
GPU for Preview Generation: Off (S3_5)

Application folder: C:\Program Files\Adobe\Adobe Lightroom Classic
Library Path: L:\Lightroom\Lightroom Catalog - Copy-v15.lrcat
Settings Folder: C:\Users\sgpfw\AppData\Roaming\Adobe\Lightroom

Installed Plugins: 
1) AdobeStock
2) DxO OpticsPro 10
3) DxO OpticsPro 10 Importer
4) Flickr
5) HDR Efex Pro 2
6) Negative Lab Pro
7) Topaz Photo (Studio)

Config.lua flags: 
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Adapter #2: Vendor : 1414
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AudioDeviceIOBlockSize: 1024
AudioDeviceName: System Default - Højttalere (Realtek(R) Audio)
AudioDeviceNumberOfChannels: 2
AudioDeviceSampleRate: 48000
Build: LR5x31
Direct2DEnabled: false
GL_ACCUM_ALPHA_BITS: 16
GL_ACCUM_BLUE_BITS: 16
GL_ACCUM_GREEN_BITS: 16
GL_ACCUM_RED_BITS: 16
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GL_MAX_3D_TEXTURE_SIZE: 16384
GL_MAX_TEXTURE_SIZE: 32768
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GL_RED_BITS: 8
GL_RENDERER: NVIDIA GeForce RTX 2060/PCIe/SSE2
GL_SHADING_LANGUAGE_VERSION: 4.60 NVIDIA
GL_STENCIL_BITS: 8
GL_VENDOR: NVIDIA Corporation
GL_VERSION: 4.6.0 NVIDIA 610.62
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Hi @quirky_projectf12e and @alexskunz,

Thank you for the exceptionally detailed testing and measurements. Before I consolidate this for the product team, I’d like to establish the behavior on the latest available components.

Please update to Camera Raw 18.6 and check whether it appears under LrC Help > System Info. If macOS 26.7 is available for your Mac, please update to that as well and repeat the same test.

You don’t need to repeat the entire investigation. A shorter controlled test would be enough:

1. Quit and relaunch Lightroom Classic.

2. Confirm GPU acceleration is enabled using the same settings as your original test.

3. Navigate through the same 5 previously edited images in Develop without making any new edits.

4. Record Lightroom’s physical-memory usage after each image.

5. Stop navigating and leave Lightroom idle for about 5 minutes, then record the memory usage again.

Please also capture Help > System Info > Copy immediately after the test and paste it here. That will give us the exact Lightroom Classic, Camera Raw, macOS, and GPU configuration corresponding to the new measurements.

One additional comparison would be particularly valuable. Since you mentioned that some of these images contain existing masks/Remove/AI-related edits, could you repeat the short test with 5 otherwise comparable RAW files that have only basic Develop adjustments and no masks, Remove edits, Denoise, Lens Blur, or other AI edits?

If memory remains relatively bounded with those files but grows substantially when walking through the previously AI or mask-edited files, that gives us a much narrower reproduction case. If both sets exhibit the same accumulation, that’s equally useful.

There’s no need to reset preferences, rebuild previews, reinstall Lightroom Classic, or perform other general troubleshooting at this point. You’ve already provided enough evidence that I’d rather keep the test environment controlled.

@alexskunz, since you’ve confirmed the behavior on an M2 Max as well, please run the same shortened test and include your System Info if possible. Having matching results from M1 Max and M2 Max systems would be particularly useful.

Once we have the results from the current Lightroom Classic/Camera Raw combination, I’ll consolidate the reproduction details for the product team.

Thanks again for the very thorough report.

Best,

Anshul Saini

I've spent a couple of hours researching this thinking it was some other process i was doing and it's causing some memory issues and eventually maxing out my swap memory on my m1 max 64GB Ram macbook pro. Please advise (using Tahoe 26.5.1 (25F80))

Title: Lightroom Classic 15.5.1: Progressive physical-memory accumulation during Develop navigation with GPU acceleration enabled; memory remains retained while idle

Summary:
On Lightroom Classic 15.5.1, simply navigating through previously edited RAW photos in Develop, without making any new edits, causes Lightroom's OS-measured physical footprint to increase by several gigabytes per image. In a clean reproduction, Lightroom grew from ~1GB to ~31GB after viewing five images. No material reclamation occurred during a three-minute idle period. The same behavior reproduced on 15.5, where Lightroom reached ~48-51GB and remained at that level for ten minutes idle; quitting and relaunching Lightroom reset the process footprint to ~946MB.

Disabling Use Graphics Processor dramatically changes the behavior: on the same first two images, GPU-enabled Lightroom grew by +13GB and +6GB, while GPU-disabled Lightroom grew by only +1.7GB and +0.6GB. This strongly implicates Lightroom Classic's GPU-accelerated Develop path.

In ordinary editing sessions this progressive footprint growth eventually produces macOS memory compression and multi-gigabyte swapouts, corresponding with severe Lightroom sluggishness/freezing.

Environment:
- Lightroom Classic version: 15.5.1 [202608131348-cab7eed5] (also reproduced on 15.5 [202607291506-b8869fa7] before updating)
- Camera Raw: 18.5.1 [2687]
- macOS: 26.5.1 (25F80)
- Hardware: Apple M1 Max (arm64), 64GB unified memory — Adobe's documented minimum for full GPU acceleration/AI features on Apple Silicon is 16GB; this system has 4x that
- GPU config tested: Custom, with Display/Image Processing/Export all enabled and Preview Generation set to Auto (a valid, Adobe-supported manual configuration — Lightroom's own UI confirmed "Full graphics acceleration is enabled")
- Catalog: ~5.1GB, local SSD, no network/cloud storage involved
- Measurement tools: Lightroom's own Preferences > Performance > System Info panel, and macOS's `footprint` command-line tool (reports phys_footprint, the same physical-memory accounting macOS uses for memory-pressure and jetsam decisions)

Steps to reproduce:
- Launch Lightroom Classic fresh (confirm low baseline memory via Activity Monitor or footprint)
- Open a catalog containing photos with substantial existing, saved Develop-module edit history (prior local retouch/heal work, correction masks — some with Remove/AI-related edits from earlier sessions). Performing a new AI/Remove operation during the reproduction itself is not required
- In the Develop module, navigate to a previously-edited photo, let it render a few seconds
- Navigate to a different previously-edited photo, repeat for 4-5 photos total, viewing only — no new edits
- At each step, check Preferences > Performance > System Info for "Dedicated GPU memory used by Lightroom," and independently check `footprint -p <pid>` for phys_footprint

Expected result:
Memory should remain bounded, or be reclaimed sufficiently, that ordinary Develop navigation does not progressively consume tens of gigabytes of physical memory and drive macOS into compression/swap.

Actual result:
Physical memory footprint climbs steadily across successive images and shows no material reclamation over the idle periods tested, even though the per-image entries in the System Info "Cache1" list do change/rotate as you move between photos. The total physical footprint is not accounted for by what's visible in that panel.

Data — GPU acceleration ON, version 15.5.1, fresh launch:
- Baseline: 194MB GPU-reported / 1.05GB phys_footprint
- Photo 1 (aar05249.ARW): 7.9GB GPU-reported / 14GB phys_footprint (+13GB)
- Photo 2 (aar05189.ARW): 14.2GB GPU-reported / 20GB phys_footprint (+6GB)
- Photo 3 (aar05367.ARW): 19.0GB GPU-reported / 25GB phys_footprint (+5GB)
- Photo 4 (aar05078.ARW): 20.2GB GPU-reported / 27GB phys_footprint (+2GB)
- Photo 5 (aar04996.ARW): 22.9GB GPU-reported / 31GB phys_footprint (+4GB)
- +1 min idle in Library view, no navigation: 31GB (peak 34GB), no change
- +2 min idle: 31GB (peak 34GB), no change
- +3 min idle: 31GB (peak 34GB), no change
- No new edits, exports, or AI operations were performed during this sequence — only viewing already-edited photos

Data — same test on 15.5 (before updating to 15.5.1), same pattern, larger absolute numbers:
- Growth across a comparable 5-6 image sequence (phys_footprint, peak in parentheses): 30GB (31GB) -> 33GB (37GB) -> 42GB (42GB) -> 51GB (51GB)
- After navigation stopped, footprint settled to 48GB (peak 54GB), then held at exactly 48GB for a separately-logged, full 10-minute idle period with zero photos touched
- Quitting and relaunching Lightroom immediately reset phys_footprint from 48GB to 946MB, demonstrating a full quit/relaunch reliably reclaims the memory; no other reclamation action was tested

Data — GPU acceleration OFF (Preferences > Performance > Use Graphics Processor > Off), version 15.5.1, fresh launch, same photos:
- Baseline: 0MB GPU-reported / 912MB phys_footprint
- Photo 1 (aar05249.ARW): 0MB GPU-reported / 2.65GB phys_footprint (+1.7GB)
- Photo 2 (aar05189.ARW): 0MB GPU-reported / 3.25GB phys_footprint (+0.6GB)
- Compare to the same two photos with GPU on: +13GB and +6GB respectively — roughly a 7-10x smaller increase with GPU disabled
- Idle reclamation with GPU disabled was not separately tested, so this speaks only to growth rate, not whether GPU-off allocations are themselves fully reclaimed

Additional context:
- Related but not identical: an existing report describes GPU memory filling during Panorama/HDR merge and not being released until Lightroom is restarted (community.adobe.com/t5/lightroom-classic-discussions/hdr-panorama-merging-ram-not-being-released). Adobe's response there was to ask the reporter to test under 15.5. This report reproduces the same underlying retention pattern via a different trigger — ordinary Develop-module navigation, no Panorama or HDR involved — confirmed still present on 15.5.1
- Adobe's published fixed-issues list for the 15.x line does not mention this Develop/GPU memory-retention behavior as addressed

Why this matters:
This reproduces from ordinary use of the Develop module on hardware well above Adobe's own stated minimum for full GPU/AI feature support. In real editing sessions working through a shoot of dozens to hundreds of photos, this progressive footprint growth has been independently measured (via a custom 1-second-resolution system sampler run over several days of normal use) to correspond with macOS memory compression and eventual multi-gigabyte real disk swapouts, alongside severe application sluggishness — observed on multiple separate occasions, both before and after updating to 15.5.1.

Full minute-by-minute and second-by-second system telemetry covering this entire investigation is available on request.

Confirmed on an M2 Max machine on Tahoe 26.6.2