2 Replies Latest reply on Jun 21, 2015 11:01 AM by willanywork

    DNG conversion in LR CC takes a long time

    willanywork Level 1

      I'm a long time user of Lightroom who has installed LR 2015 CC (and 2015.1) and have found that the time to upload, convert to DNG, and create Standard previews has increased DRAMATICALLY.  I'm thinking I've missed something but cannot figure out what it is.


      My computer is  


      Model Identifier:    iMac10,1

        Processor Name:    Intel Core 2 Duo

        Processor Speed:    3.06 GHz

        Number of Processors:    1

        Total Number of Cores:    2

        L2 Cache:    3 MB

        Memory:    12 GB


      The problem:  It takes 5 hours in LR CC 2015.1 to upload 378 33 MB .RAF (X-T1 Fuji raw) files for conversion to DNG and creation of Standard previews and only 2 hours in LR 5.7.1. Mobile sync, address lookup and face detection are all paused. During processing both cores are running at 98 to 100%.


      I have tried doing each step separately and found that upload only takes 20 minutes but that DNG creation takes something more than an hour (Something less than half done at one hour and I just quit). I did not even try to create standard previews. It doesn't look that doing each step separately would have any benefit.


      Any suggestions and guidance would be greatly appreciated.

        • 1. Re: DNG conversion in LR CC takes a long time
          Jao vdL Adobe Community Professional & MVP

          I have seen several reports of this now. Something changed with dng creation in Lightroom that makes it terribly slow. My guess is that this is a bug.

          • 2. Re: DNG conversion in LR CC takes a long time
            willanywork Level 1

            I have done some more testing and have found that in a 4 core machine with SSD storage the issue is in DNG conversion of the 378 image dataset.  The creation of Standard Previews only took seven minutes and the DNG conversion took over an hour.  There is a significant difference between 2 and 4 core processors.  The two core processor on the iMac ran at almost 100% for the time to create DNG and Previews with the two processes concluding close together.  In the four core machine the cores were running about 70%.


            I have read on another thread that Adobe changed the way LR processes DNG files so that the process requires two writes and one delete to finish each conversion.  This was done because of some perceived file corruption issue.