The 1DX III files and likely the R5 files put a lot more processing load on the system than previous cameras.
I have 1DX, 1DX II, and 1DX III models and the 1DX III files are clearly significantly more processor intensive. I am using a HP Z 840 workstation with twin Xeon 6 core 3.4 Ghz CPUs with 256 GB of ram per CPU. Maximum processor load peaks briefly at 30-34% before staying in the low 20% range until processing is finished in a few seconds. DPP and the image files are run from a HP Z turbo solid state drive plugged into the PCI bus.
It is disappointing that DPP still takes little advantage of the Nvida Cuda cores. This system has a pair of Nvidia Quadro 4000 workstation cards with 1,664 Cuda cores per card and GPU loading stays at 3% or below with most of that used by other system processes. The Nvidia monitor shows that DPP is running on the GPU but it is doing pretty much nothing with it. Hopefully Canon's software supplier addresses that in the future.
I have tried using Canon's cloud noise reduction but it doesn't seem to produce any better/different results than I get with the DPP local process and it isn't any faster. It is likely more useful on systems with less available resources.