All I can tell you is with the tools I have at my disposal to test with, the RAW files from my Nikon D850 and M2P take ~8-10 seconds to open in Affinity on my 11" iPad Pro 2018 256GB. It's about the same with the Lightroom app. As someone who edits hundreds of RAW files at a time, going one-by-one like that would be simply impossible. For a single image edit for sharing on Facebook or whatever, it's fine. Editing is also not in real-time, and while certain effects are being applied, the image shifts from extremely poor resolution back to it's proper resolution while you move the sliders because it cannot render it instantly - maybe this is less noticeable on the iPhone 8, I don't have one to test with. With a M2P RAW file in Affinity, moving the sliders to adjust image properties shifts the image away from it's native resolution and it does not happen in what I would call real-time. It doesn't give me any trouble really, it just performs exactly as I would expect it to given the hardware limitations and what I am asking it to do.
JPEGs are less of an issue, and generally much snappier, as they should be, being tiny 8bit files with very limited processing leeway.
Nothing will batch edit on the iPad like you can on a PC, unfortunately. Not even Adobe's "fully featured" Photoshop app that is apparently coming at some point, unfortunately lacking many of the most critical features of desktop Photoshop (batch processing, custom color profiles, the thousands of available plug-ins, etc.)
I have a $6K PC custom built for photo/video editing, so any comparisons I do are not really fair. The iPad Pros can indeed render video pretty quickly, as I mentioned above, on the video side their limitations are less severe. The hardware limitations of the iPad are for the most part objective and physics based (wattage, clock speed, core count, etc.) Certain tasks can be performed very fast though due to heavy optimization, such as a video render. On top of this our hot water tank burst a couple weeks ago, and everything is out of the basement, including my PC
Thankfully it did not get destroyed, but it'll be a while before I can do any testing with it haha.The iPad also doesn't have a true file system. It has the files app, but it is nothing like an actual file system that you find on Windows OS, for example. You can't even do the simplest imaginable file-related tasks, such as drag & drop photos from a portable hard drive into a folder of your choice. Everything is funneled through the Photos app, which can't even display EXIF data. Apparently iOS 13 is going to add a lot of much needed functionality to the iPads making them more like the "laptop replacements" they are advertised as being. We will see. I love my iPad Pro 11", don't get me wrong, but some of it's limitations definitely frustrate me still and a laptop replacement it most definitely is not.
Typical photo editing would go something like this - import hundreds of 14bit RAW files into ACR from my D850, and go through them batch-applying custom Colorchecker profiles to the similar photos, correcting WB, batch applying certain adjustments, lens corrections, etc. Then bring them into Photoshop if necessary to use various plug-ins on them, etc. From start to finish, the entire typical professional photo editing workflow is literally impossible on an iPad. On top of that there is no way to properly calibrate the screen, which is an issue if you're doing critical paid work, prints, etc. Hopefully some of that functionality is eventually added, but between the weak (relatively speaking) hardware and mobile OS, it just doesn't have the ability at this juncture.
For comparison's sake, here in Canada you can regularly buy a Dell XPS 15 with 6-core i7 8750H CPU (35W), 16GB RAM, Nvidia 1050Ti 4GB GPU, 512GB PCI-E x4 SSD, and a matte screen than you can actually calibrate for $1750 CAD/ 1350 USD. Obviously, it's bigger and heavier so the value propositions aren't identical, but performance per dollar is in an entirely different league, and it has none of the application limitations. That is what I would consider to be a pretty standard laptop and at a price that is quite a bit less than a loaded iPad Pro, and almost exactly the same price as a 12.9" iPad pro 512GB WiFi.
The addition of USB-C was long over due and a big step forward for the iPad Pros, but even that is still fairly limited in its current state.
Anyway, I think we just have different uses and expectations from our editing machines
.
