Good point @Calle
Yes, as indicated my tests included PRIME.
I ran a new test with 20 photos with 4 and then 8 photos in parallel.
8 photos in parallel is 6% faster on 32 cores than 4 photos in parallel. So great!
For general information, on my win10 64 GB memory usage idle is 13 GB.
Running 4 photos in parallel, memory usage peak is 16 GB
Running 8 photos in parallel memory usage peak is 19GB.
So DXO does not use much memory.