LrC reads raw files while scrolling in Library module

[TAP Photography]

I have noticed some delays in displaying previews while scrolling thru photographs in loupe mode in the library module. The preview appears pixelated for a short time, then clears up. Standard previews are created during import (2880px).

I then looked at CPU/Disk activities and saw, that LR is constantly reading the raw files of the photographs I looked at in the library module.

Attached are some screenshots from Task Manager and Activity Resource Manager:

- CPU activity is very high during the scrolling

- in tandem to the CPU activity, disc activity on disc G: (where the raw files are located) is very high

- disk activity on drive D: (where LR catalog is located) is very low

- Resource Monitor showing LR reading all the raw files

During scrolling in the library module, I would expect LrC to read only the previews it has previously generated, not the raw files.

The question is, why is LrC reading the raw files when there is no reason to do so?

Does anyone have an idea/explanation for this behaviour?

LrC 12.5

Windows 11 - 22621.2134

NVidia Studio-driver 536.99

[Ian Lyons]

You've only mentioned the preview size you create during import, but this may not be large enough, espcially if using Full Screen mode. For example, if the screen resolution is greater than the preview resolution, then LrC may need to update the existing preview as you loupe through the images. 

[TAP Photography]

I am viewing on a 2k monitor (2560x1440 px) so the preview size is sufficient. 

I 'm going to verify if/that LR is writing to the preview files during the scrolling. 

[dj_paige]

During scrolling in the library module, I would expect LrC to read only the previews it has previously generated, not the raw files.

The question is, why is LrC reading the raw files when there is no reason to do so?

Does anyone have an idea/explanation for this behaviour?

Perhaps LrC has deleted the previews after a certain period of time. This is a setting you can change in Catalog Settings. Or perhaps the previews haven't been generated yet, if this is immediately after (or during) import. Or perhaps (I'm guessing on this one) LrC sees the 2880 px preview and says to itself that it can't use that on a 2560x1440px screen so it has to create a new preview.

[TAP Photography]

this problem continues...

I just imported 423 photographs and let LR create all the standard previews (2880px). Once the previews were created, I deliberatly choose "Library-Previews-Build Standard-sized previews-Built all" - no previews were created now, meaning that all previews are already rendered.

Now, while scrolling thru the photographs in Loupe View, maybe two photographs are displayed correctly, then the next one is first pixelated, then showing a preview, then rendering the correct preview (while showing Loading...). And this continues for all other photographs.

By the way, this is another catalog then the one I was using before, more or less excluding the possibility of a catalog-related issue.

Any idea what is happening here?

[D Fosse]

I'm guessing the previews are there, but reading the cache is slow. Maybe the cache is corrupt in some way. I'd try to delete the cache and let it rebuild. This is already slow generating the preview, so there's nothing to lose.

[TAP Photography]

it is definately not reading the previews but rendering them again from scratch - happens again with another import of 1100 photographs and after having already rendered all previews.

Next try will be creating a new catalog and I will see what happens there