Inspiring

Answered

NEF Previews crazy slow

Forum|Forum|7 months ago
August 9, 2025
3 replies
428 views

I have LR 14.4 and a new Nikon Z8 with 45 megapixal images. I recently switched back to Nikon from a Sony A7R (42 megapixel). I run LR on a 2019 maxed out IMAC (all SSD and 16GB RAM). Yes, it's not the newest in the world, but it handled the Sony RAW files just fine. Building previews took 2-4 seconds per file, so uploading 1000 RAW files took about an hour to generate all the previews. Note, I haven't used my Sony for big shoots in a while, so these times are with an older version of LR.

I just uploaded 250 files from my Nikon and it took an hour to generate the previews (10-17 seconds per file). All 6 cores were at 100%, and even though I have "Use Graphics Processor" on Auto (It says my system fully supports acceleration), my GPU history shows that the GPU is not being touched while building previews.

Does LR only use the GPU on Apple M chips and no longer Radeon or Intel? This is way slower than it used to be.

macOS

Correct answer DaveDuprePhoto

Version 14.5 allows you to turn on the GPU for previews. If you turn it ON (vs. Auto), my preview generation takes around 1 second per file. Thank you Adobe!

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DaveDuprePhotoAuthor

Inspiring

For now, I will need to switch to using the embedded previews on import. Then only build standard previews after a round or two of culling.

Just imported 129 images, and after 15 minutes, it is only on image 40 -- 20+ seconds per file. Next airshow I come back from with 3000 images will take 16+ hours at this rate. Is it NEFs, or did Adobe really slow things down that much? With my Sony A7RIII (42 megapixels vs the Z8's 45) it never took anywhere near that long on the same computer. As I said above, that was with all my images on a NAS vs a fast SSD now.

D

DaveDuprePhotoAuthorCorrect answer

Inspiring

Version 14.5 allows you to turn on the GPU for previews. If you turn it ON (vs. Auto), my preview generation takes around 1 second per file. Thank you Adobe!

dj_paige

Legend

GPU is not used when building previews at Import. Still shouldn't take as long as you are seeing.

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DaveDuprePhotoAuthor

Inspiring

Interesting part I just remembered. Back when I was processing thousands of photos from my A7RIII, all my photos were on a NAS, and it still was faster. I forgot I I've only picked up an external SSD (2000MB/s) since June. So that's a drive that is 16x faster (1000 Mb/s vs 2000MB/s -- small b for bits vs big B for bytes).

I wonder if it's just Nike NEFs vs. Sony ARW processing. The Nikon Z8 NEF is newer and not fully tuned yet? Then again, it has been 2 years since the Z8 came out.

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DaveDuprePhotoAuthor

Inspiring

FYI, the A7RIII is not build for speed, but I still used it for my kid's hockey and volleyball, and then I also went to a bunch of warbird air shows. Each session easily brought in 1000-3000 photos. The Z8 at 20 frames/sec will almost not be processable for my next air show.

johnrellis

Legend

LR does use the GPU on Intel Macs. Please do the LR menu command Help > System Info and copy/paste the entire contents here so we can see exactly which versions of hardware and software LR thinks you're running and important LR options that are set.

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DaveDuprePhotoAuthor

Inspiring

Preview size is set to Auto, which looks to be 5120px. It's been on auto forever (10+ years).

Lightroom Classic version: 14.4 [ 202506051112-5918896a ]
License: Creative Cloud
Language setting: en-US
Operating system: Mac OS 15
Version: 15.6.0 [24G84]
Application architecture: x64
Logical processor count: 6
Processor speed: 3.7GHz
SqLite Version: 3.36.0
Built-in memory: 16,384.0 MB
Dedicated GPU memory used by Lightroom: 1,162.8MB / 8,192.0MB (14%)
Real memory available to Lightroom: 16,384.0 MB
Real memory used by Lightroom: 5,161.4 MB (31.5%)
Virtual memory used by Lightroom: 60,073.8 MB
Memory cache size: 1,218.2MB
Internal Camera Raw version: 17.4 [ 2272 ]
Maximum thread count used by Camera Raw: 4
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 2590MB / 8191MB (31%)
Camera Raw real memory: 2684MB / 16384MB (16%)

Cache1:
Final1- RAM:352.0MB, VRAM:0.0MB, 20250802-silver-lake-park-029.NEF
NT- RAM:352.0MB, VRAM:0.0MB, Combined:352.0MB

Cache2:
m:1,218.2MB, n:352.1MB

U-main: 171.0MB

Standard Preview Size: 5120 pixels
Displays: 1) 5120x2880

Graphics Processor Info:
Metal: AMD Radeon Pro 580X
Init State: GPU for Export supported by default
User Preference: Auto
Enable HDR in Library: OFF

Application folder: /Applications/Adobe Lightroom Classic
Library Path: /Users/dave/Lightroom/Lightroom Catalog-v13-3.lrcat
Settings Folder: /Users/dave/Library/Application Support/Adobe/Lightroom

Installed Plugins:
1) AdobeStock
2) Any Tag
3) Aperture/iPhoto Importer Plug-in
4) Flickr
5) jf Collection Publisher
6) jf Folder Publisher

Config.lua flags:

DdeGannes

Community Expert

On my iMac 27" I do not have Preview size to auto see the screen capture.

I find that adequate for general use if you need to compare in Library Module you can generate 1: previews. In develop Module the raw file will be used to render the image.

Regards, Denis: iMac 27” mid-2015, macOS 11.7.10 Big Sur; 2TB SSD, 24 GB Ram, GPU 2 GB; LrC 12.5,; Lr 6.5, PS 24.7,; ACR 15.5,; (also Laptop Win 11, ver 24H2, LrC 15.0.1, PS 27.0; ) Camera Oly OM-D E-M1.

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