I shot my first studio session yesterday, tethered. I took 1150 images and LR had no problems at all in handling the load as they were imported from the watched folder.
As discussed in a previous post, files from a tethered shoot are imported as there native RAW file, in my case CR2's.
The problem arrose when i got home and went to convert all of them to DNG.
LR got about 1 hour and 360 images into the process and refused to convert any more. "Lr was unable to convert this file to DNG"
No matter what i tried it failed to convert any further images. I rendered all standard previews. I optimised, nothing.
It was not the CF cards, as the point where it stopped was 1/2 way through the 2nd of 4 cards
Luckily, i made sure before the shoot to tick the box in my EOS capture not to delete files from card during capture/import.
In the end i had to import all the images that were not converted initially from my CF cards.
All up this process took me 4 hours, where instead i should have been working on developing some images to show to the client this morning.
Well unless you bother to state the basics...like LR version, OS, all you are doing is venting uselessly. If you want help, I suggest the Lightroom forum down the hall as this is a Lightroom issue, not a DNG issue.