LrC 14.5.1 significant increase in size of the lrcat-data folder

Question

Can anyone provide an insight why my Lightroom Classic lrcat-data folder has doubled in size following the updating of Lightroom Classic to v14.5.1. I became aware of this when I realised it was taking longer to copy the Lightroom backup zip file created when closing Lightroom to an external USB drive.

Using the contents of the zip files then:

26th August 2025, immediately before the update, the lract-data folder in the backup contains 8 blob files, total size 622MB
29th August 2025, after the update, the lract-data folder in the backup contains 10 blob files, total size 1.22 GB

During this time no new photo's were added to the catalogue and no significant editing was done.

The most recent backup taken today, 5th September 2025 contains 10 Blob files, total size 1.21GB

johnrellis · Accepted Answer

I'm looking for an additional reason for 600 MB growth in the lrcat-data folder. I agree AI Denoise will be a contributory factor but a metadata search for photo's using 'has denoise set' identifies 30 photo's. 1 had it applied in 2024 and the rest in 2025, 9 in March, 19 in July and 1 in August

@Mark316864980bup: "I'm looking for an additional reason for 600 MB growth in the lrcat-data folder. ... 19 in July and 1 in August"

Only images denoised in LR 14.4 and later will contribute to the size of the .lrcat-data file. In your case 600 MB / 20 images = 30 MB / image on average. That's well within the expected range of 4 - 56 MB per image. The size depends primarily on the image resolution and the amount of detail (not on ISO). See here for more details:

https://www.lightroomqueen.com/community/threads/new-denoise-feature.52986/page-5#post-1355236