Inspiring

Question

Performance Issue on Silicon iMac Since LRC 14.4 update

Forum|Forum|7 months ago
August 28, 2025
3 replies
682 views

My problem is as follows.

Any RAW (NEF) image I use the new AI denoise on and start editing slows my M1 iMac down considerably to a point where the cooling fan noise is very noticeable and system performance very sluggish to the point where LRC becomes unusable.

It should be noted that any RAW images I don’t use denoise on is fine, so I have to stress it only happens when editing an image with denoise applied.

I tried all sorts GPU acceleration ON/OFF, GPU for display, increased Camera RAW cache sizes etc. only all to no avail. I did see some users reporting similar issues with both Windows and Macs on the Lightroom Queen forum but there haven’t been any satisfactory resolutions. The two recent updates to 14.5 and 14.5.1 this week haven't helped in fact if anything have made the situation worse.

Using the MacOS System monitor shows CPU useage at over 400% with a denoised and edited image but less than 10% when no denoise applied.

As I said above for me the LRC latest release is currently unusable and I have again reverted back to the last release which worked with no issues whatsoever i.e. 14.3.1 and all is fine again, for info CPU useage with this is never creater than 30% when editing.

I can live with using DNG’s for a bit longer in the hope Adobe provide a resolution in the near future

If helps a basic iMac System report is attached.

Current MacOS is Sequoia 15.6.1 is being used.

Thanks for any help or info that can be provided.

Regards

Gordon Speirs

iMac.pdf

macOS

E

ExUSA

Legend

I have an M1 mini, similar specs to yours, and do not see this happening. Are all of your files on local hard drives? Are you writing changes to XMP automatically?

dj_paige

Legend

Any RAW (NEF) image I use the new AI denoise on and start editing slows my M1 iMac down considerably to a point where the cooling fan noise is very noticeable and system performance very sluggish to the point where LRC becomes unusable.

Yes, this happens because you are requesting the system to do a lot of work (denoise is a lot of work) on many images, and this generates heat, and so the cooling system (fans) turns on. If it continues getting hotter, then the computer "throttles" (deliberately slows itself down) to prevent overheating. This sounds like it matches your symptoms exactly.

If you can open the case on your Mac, make sure all the fans are spinning properly, and vaccuum out the inside and also vaccuum out any dust or other obstructions in the air vents in the case. Make sure the computer air vents are not blocked by furniture or a wall. If it is a laptop device, try a laptop cooling device as described here: https://www.dpreview.com/forums/post/65523199

S

stropy jockAuthor

Inspiring

Hi,

Thanks, its an iMac so not a laptop and vents are the bottom are clear etc.

Yes being an electronics engineer I understand about about processors and the need for fans and heatsinks for cooling etc.. Just to clarify this is just when operating on ONE file not many and only when denoise has been applied. If no denoise and edited all is good.

Thanks for the reply, just trying to understand what has happened between v 14.3.1, v14.4 and v14.5 etc.

From what I have read elsewhere other folks are reporting similar issues but I haven't found a solution as yet despite trying several recommended steps.

Thanks again.

dj_paige

Legend

Hi,

Thanks, its an iMac so not a laptop and vents are the bottom are clear etc.

Yes being an electronics engineer I understand about about processors and the need for fans and heatsinks for cooling etc.. Just to clarify this is just when operating on ONE file not many and only when denoise has been applied. If no denoise and edited all is good.

Thanks for the reply, just trying to understand what has happened between v 14.3.1, v14.4 and v14.5 etc.

From what I have read elsewhere other folks are reporting similar issues but I haven't found a solution as yet despite trying several recommended steps.

Thanks again.

By @stropy jock

You have the exact symptoms of throttling. Even though you are denoising only one photo, the heat has clearly built up, causing the fans to come on and causing throttling; and will probably take a while to dissipate. Hot metal parts do not cool off instantly.

The Denoise code has clearly changed between 14.3 and 14.4, and probably again between 14.4 and 14.5 as Adobe tries to speed up denoise, so comparisons aren't really valid. But something else might have changed ... perhaps some aspect of your cooling system has failed somewhere along the way, and 14.3 doesn't create enough heat for the failure to make a difference, but 14.5 does create so much heat that the failure does make a major difference.

Sameer K

Community Manager

Hey Gordon! Welcome to the Lightroom Community. I need more information to help you understand this.

Please share the system info from Lightroom Classic from Help > System info > Copy and paste into a text document > Upload and attach here.

Where do you keep the Lightroom Catalog and NEF files? Internal, or external drive?

Check if you have enabled the following option in Catalog > Metadata > Automatically Write Changes Into XMP?

Try these suggestions:

1 - Create a new catalog by holding the OPT/ALT key at the launch of Lightroom Classic.

2 - Go to File > Import from catalog > target your old catalog. Proceed with merging the previous catalog into the newly made, internal storage-based catalog. For more help via video-based steps, check here. See https://adobe.ly/3NTC9Rv

Let me know how it goes. Thanks!
Sameer K

(Type '@' and type my name to mention me when you reply)

S

stropy jockAuthor

Inspiring

@Sameer K

Hi Sameer,

Thanks for responding.

I won't be able to provide all the details for a few days and will provide the LRC system info on this thread as soon as I can.

In the interim I can answer a sime of your questions.

The vast majority of NEF files are on the internal Mac SSD but I do have another SSD connected externally.

Automatically write changes into XMP is currently disabled, also Camera RAW cache has been cleared and is now set greater than 20Gb.

I will try the steps you suggest when I am back home in a few days.

Thanks again.

Gordon

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