Photo switching performance in Develop mode is slow

[GdzieJestStach]

Can you please fix the very slow photo switching speed in Develop mode?

In Library mode photo switching is instantaneous, but in Develop mode it takes 1 to 2 seconds (!) to change photo. During that time I can see UI updating slowly, all sliders graying out and coming back to life.

It's really disrupting my workflow, especially when I want to quickly compare two virtual copies of the photo to see subtle differences I've made.

This behaviour is always so slow for all versions of LRC in the past years, no matter what hardware I used (eg. powerful PC with 4070, or MacBook M1).

Look at how fast Capture One photo changing works.

[GoldingD]

Please post a screenshot of your LrC /preferences/performance 

[GdzieJestStach]

Here is attached video demonstrating the performance and settings.

First I demostrate in Library mode, then change to Develop.

Initially GPU usage is set to auto. Later I change it to CPU.

When on CPU, initial photo change is instant, on GPU it's much slower.

But on both the UI sliders take long time to update. I belive the slow performance of photo switching is due to slow UI elements update, which should definitely not be a problem - it should be instantaneous.

[GoldingD]

Can you please post just a screenshot of /preferences/performance/ The one in the video is to blurry to read.

Also, I recommend for a small file such as an image, to use the Insert Photos button instead of the attachment buttons. They work better on this site.

from: Community How-To Guide - Tips & Best Practices

Add screenshots, images, and attachments

As a best practice, please add images (jpeg, png, etc.) via the Insert Photos tool

Upload your image by clicking on Choose Files, select the formatting and the size, and select Done. 

[GdzieJestStach]

I tried using smart previews, but with same performance.

[GoldingD]

I inquired about that part of the preferences as to see if anything was a bit odd. Looks Ok.

And I inquired as to see what was set for Camera RAW CACHE.

Many members with develop module performance issue have that set to the default of 5 GB (too low for most everyone). Your value of 20 GB is often the recommended amount for general use. Some advise higher, more like 50 GB.

Issue is mostly if the Camera RAW CACHE gets filled up. You might want to check the CACHE for just how much of that limit is filled up.

I thought there was a web page by a landscape photographer that discussed how to determine Camera RAW CACHE size vs number of photos in an edit session, but Nope, can not find. Many just set it as high as they feel comfortable in terms of sacrificing hard drive space. (does anyone have a link??)

I will share the following link that discusses clearing the CACHE for various reasons, one being performance. Mind you performance after clearing the CACHE may take an initial hit as the CACHE will nee to be rebuilt after that (one by one as the photos are selected) I would think this would be a consideration if the performance was way way slower than what you are seeing.

https://weddingrebels.co/blogs/lightroom/how-to-clear-lightroom-cache

Another consideration is the location for that Camera RAW CACHE. I see yours is on the C drive on a Windows computer. I have no idea if that is a SSD. The catalog and the CACHE can take advantage of being located on a SSD (the photos not so much). Also, on a Windows PC placing the CACHE on the C drive might have read/wright competition with the Windows Paging file, this would be a small hit in develop module performance. Relocating the CACHE to a different drive might help.

[GdzieJestStach]

I've purged cache and removed previews file. Also deleted most photos from catalogue, leaving around 1000 in total.

Still same performance - 1-2 seconds to switch photos in develop mode.

What really makes me wonder is that switching back and forth between two photos should really be instantaneous. Both photos are fully rendered and should be in immediate cache in RAM and VRAM. But! Lightroom prefers to render them from the beginning, resulting in 1-2 seconds delay. WHY!?

[Conrad_C]

In any module except Develop, an image is displayed from the preview cache, and previews are compressed JPEG images. If a preview is built, it should display instantly. If a preview is not yet built, there may be a delay. The delay can be shorter or longer depending on the preview quality and resolution set in Catalog Settings / File Handling.

In Develop, for the most accurate image display while editing, an image is not displayed from the preview cache of compressed JPEGs, but is re-rendered completely from the original raw data at maximum quality. This is why it generally takes longer than in any other module, and why Adobe had to add GPU acceleration to some areas of Develop. How many megapixels are the images? Because the delay is not too bad for me, but many people now use cameras that capture many more pixels than mine and that would add to the rendering load.

The initial display in Develop might be slightly faster if the current version of the image already exists in the Camera Raw cache, or if Lightroom Classic is set to load a Smart Preview and it exists.

It would still be nice if Adobe could speed up Develop, but given the reasons above, Develop will probably never be as fast as the other modules as long as Develop renders full quality from raw.

[GdzieJestStach]

Somehow in Lightroom (not Classic) on desktop and on iPad, this full render from RAW is very fast, almost instantaneous. Switching photos there is as fast as in Library in LRC.

Also, LRC rendered RAWs from the same camera with the same speed few years ago on much, much slower machine.

It seems it doesn't depend much on hardware speed.

It's good to have perspective, recent games can render ridiculous graphics 100 times per second, so I believe LRC should be able to render a small 20 mb RAW in less than a second.

[dj_paige]

For most people, LrC does render 20 mb images in about a second, but it would still depend on what edits, and what types of edits, have been previously applied to the image. Your comparison to games is not valid, LrC and games work differently under the hood.

Please try this solution: https://community.adobe.com/t5/lightroom-classic-discussions/slow-to-launch-and-walk-between-photos/...

[CumberLinda]

That kind of slowness isn't seen by everyone. I can advance in Develop in a split-second. If you've seen this lag for years and on two computers, where are your image files stored? Where is the catalog? How full are the internal drives? It might be catalog corruption if you're using the same catalog on both computers (neither of which should be slow). Do you optimize and check integrity when you create a catalog backup?

[D Fosse]

Develop switching is virtually instant on my two Windows machines, with 60 MP raw files. Yes, there is a barely perceptible lag, but not so much that it's ever a nuisance.

So this isn't universal.

The OP mentions that it's the same in both a Windows machine and a Mac. That's very useful information, because on two platforms that different, the common factor has to be something introduced from the outside. That is, some installed software, plugin, extension, etc etc.

The very few problems I've had over the years, have mostly been diagnosed that way. If it happens on two machines, what's common between them? If it only happens on one, what's special?

[GdzieJestStach]

Have you seen my attached video? Is it really faster on your system? Could you provide a video of that, switching between few unedited and edited photos?

On every machine I used Lightroom with all default settings, no plugins, no changes.

I've looked at some lightroom videos on Youtube and from what I see in most of them switching photos takes 1-2 seconds.

I really wish I was able to press left and right arrows and quikcly and just immediately see changes I've made to the photos, without needing to go back to Library mode.

[D Fosse]

Checking against shutter speeds on my camera, it's between 1/3 and 1/2 second to switch between frames in Develop. This is advancing from one frame to another, having the image up, and all LrC controls ready to go. 

Sony a7rV at 60 MP, LrC 13.2, Windows 10, 2560 x 1440 display, RTX 3060.

ACR cache at 20 GB, kept on the NVMe gen 4 system drive.

Curiously, it doesn't seem very correlated to file size. Older 36 MP files aren't noticeably faster. Amount of adjustments doesn't seem to matter much either.

If you're talking about 100% preview, 1:1, fully rendered, then that's that's obviously slower, probably depending on whether it's in the ACR cache or not. About 1.5 seconds there.

[GdzieJestStach]

What do you mean 100% preview? I'm talking about moving between photos (left, right arrows, or clicking) in Develop mode. It's that 1.5 seconds in my case, which I think is about 1.4 seconds too long, seeing how powerful machines we have today.

[D Fosse]

OK, then you can just disregard my last paragraph. Then my timings are 1/3 to 1/2 second.