P: DNG Converter running out of memory (version 17.1.0.2100)

I'm experiencing the same issues, in my case with converting to DNG in Lightroom. Converting 300 photos took over an hour, using practically all of my 64GB of RAM on an Intel Ultra 9. The performance issues in Lightroom are starting to become very worrying.

This is really quite ridiculous. Are there any developers in here paying attention?  There were just 44 images and it ran out of memory for two of them.  This is on a 64GB Win11 system. There is nothing wrong with the two files that failed to convert. When I re-ran the conversion with just those two files they converted almost instantly.  I don't even exit the converter, I just click Ok, remove all of the files that converted successfully and then restart the conversion. This was with version 17.2.0.2155, but this running out of memory issue has been happening for awhile.

That is my experience but I have tried the standalone and in Bridge (I don't use LR) and have the same problem with both. It doesn't matter what I do it just throttles back when left alone. It is much faster if I am working on the computer and can keep the window of the standalone live. Like that it can do a 1000 in maybe an hour. If I leave it overnight it does about 350 in 8 hours! I have tried everything to make sure my computer isn't going to sleep when left, but it makes no difference. Completely bewildering.

Unfortunately bumping an old thread, but if it's any reconciliation, I have a 96GB Ryzen 9950X3D system and experience the same thing you do. The first 50-100 files go at a reasonable speed but then everything starts dragging and chugging once we get 100 photos in or so. I can get maybe 700 done in about 8 hours while I sleep and I'm shooting 3.5k shots a wedding... which is not ideal. 

Converting in the standalone converter seems to work faster than doing it in Lightroom. The standalone converter will at least saturate my memory, likely due to working on many photos at a time — it seems lightroom only converts one or two at a time. 

I walked away after loading tonight's session and after about a half hour came back to discover the DNG Converter still had not finished converting about 900 files. That is crazy long on my system. I noticed that moving my mouse was jerky, and that the conversion itself appeared frozen. So I aborted it. Moved all of the finished files and restarted with only 211 files left to go.

After it had finished about 100 of the images, the system was again extremely slow and the conversions were taking forever. So I brought up Task Manager. You can see what it looked like in the screen capture down below (100% cpu utilization and 87% memory).  This is on a Windows 11 machine with 64GB of memory and an AMD 3950 with 16 cores (32 threads) all of them pegged at full utilization.

I suspect the problem is a memory leak causing the DNG Converter to usurp all available memory and then the system just drives itself into the ground when there's very little memory left.

This occured using version 16.0.1.1683 with the following settings:
JPEG Preview: Full Size
Embed Fast Load Data

Don't use lossy compression
Preserve Pixel Count
Don't embed original

And this happened while processing files from my fairly new Sony a7iv  (not 'R'). 

I have had a Sony a7Riv (different from above - this one is a 60mp camera) for a couple of years now and have experienced "slow-ish" conversions, but nothing approaching this level of sluggishness nor taking over the system CPU and memory the way this one is.  So the problem might be a combination of the new camera (a7iv) and the settings I'm using (see above).

Here is a screen shot of what Task Manager looked like after converting about 100 of the a7iv images: