I operate a canon R5 but find DPP unusable for all practical purposes with IMAC. I have a top spect 2018 IMAC but find it slow to the point where it is pro all practical purposes not an option with my mac whereass it is "reasonable" on my supfacr pro 7 (with far inverior spec).
I can only assume that canon have not bothered to utilize the cores/processing power of the IMAC, so if you operate an IMAC dont bother with DPP, let it go and save yourself a lot of frustration it is not compatible with (though availible for) a IMAC.
I can totally relate... I bought the R5 and later the R6... The R5 files take a full minute to process, regardless of white type of RAW file I am processing. The R6 files take about 30 seconds each to process.. My nearly new iMac is set up.. probably pretty close to yours... I tried using Lightroom, but absolutely hated the look of the color.. I just let the computer run all night... and the following day, and the following night and the day after that to process my wedding pictures from the R5.. That should not be the case. Unfortunately, unlike any other Canon DSLR, they didn't provide us with a reduced file size to use for us who shoot a lot of events, or images that only end up being used on Instagram... and don't need to be pounding out 45mp images for images that have a max size of 1080 pixels on social medic sites... Sorry, but I shoot RAW, only, and the JPG previews are useless to me.. Canon..? Do you have that obvious flaw fixed in the next firmware..?
DPP isn't great at utilizing PC resources either but it is faster on that platform. The only major lag I experience is using digital lens optimizer with files from my 1DX III which typically take around 10 seconds for that algorithm to complete.
I am using DPP with a twin Inel Xeon CPU HP Z840 workstation with twin Nvidia workstation graphics cards and during the time it is thrashing around, CPU utilization never goes above 25% and is typically in the 10% range. GPU utilization stays at the 1 to 3% background use level. Each processor has 256 GB of memory and the program and image files are running on a DPP dedicated HP Z drive SSD on the processor bus so system memory and transfer speed aren't the issue.
Files from my 50 MP 5DS and 5DS R bodies and 1DX and 1DX II bodies are nearly instantaneous in processing compared to the 1DX III lens optimization but DPP clearly doesn't do a good job of using available resources.
DPP would be much more useful if the software were cleaned up AND if they would dump the useless "percent processed" splash screen that pops up during RAW to JPG conversion which is useful only if you want something to block the view of the next image you are trying to edit. Maybe get someone who actually does photography to participate in QC would be useful for the next DPP release 😞
I use DPP on an iMac. It appears to me to usually only use 4 CPU cores and does not use the GPU for most things. It seems to me difficult to write portable GPU code. An uncropped R5 45 megapixel file with a lot of noise reduction and digital lens optimization and color correction may take up to 12 seconds to save from RAW to JPEG quality 10 on my iMac. The additional RAM seems to me to have made the biggest difference in performance. I run DPP on the iMac, but run imagemagick, hugin, gimp, and occasionally rawtherapee on a Debian Linux machine with 4 CPU cores and 64 GB of RAM. Most of the disk storage is on the Linux machine. Some of the disk storage on the Linux machine is shared with the iMac using samba. Noise reduction, gamma adjustments, and digital lens optimization seem to me to take the most time.
Model Identifier: iMac19,1
Processor Name: 6-Core Intel Core i5
Processor Speed: 3.7 GHz
Number of Processors: 1
Total Number of Cores: 6
L2 Cache (per Core): 256 KB
L3 Cache: 9 MB
Memory: 96 GB