But tomorrow I will receive a new 12.9, and test performance of Affinity for myself. I will get back to you.
Okay, got my new 12.9 and Affinity. Here's my results, using a 50 MP Hasselblad RAW file. I would consider that a torture test. Not many people work with 50MP RAW files yet.
Disclaimer: This is not scientific, and my results have not been consistent. Maybe due to charging while installing and indexing a lot of stuff at first - ipad was quite warm. After a while timings settled at those described below.
I have the raw file stored in OwnCloud, synced to device. Affinity can open directly from there.
From clicking the file until image appears and can be viewed and manipulated: 5s +/- 0.4s
Zoom and pan is almost instantaneous, as is preview of adjustments.
Developing the file with default settings: 5s +/- 0.4s
Developing with all basic adjustments changed slightly (random): 27s
Developing with maxed out noise reduction: 50s +/- 1s
After developing:
Noise reduction preview seems instantaneous.
Noise reduction (10,30,60%) and pressing apply: 45s +/- 3s
Other functions (not using the RAW file used above):
HDR merge of 4 12MP jpegs: 16s
Panorama stitch of 4 12MP jpegs:
Preview stitch: 4s
Render panorama: 10s
One annoyance observed (could be my fault for not knowing the app very well):
When opening files for HDR merge or panorama stitch, I couldn't open images from Camera Roll. I had to copy the files to OwnCloud (or possibly similar) to be able to open them, and then I could only insert one image at a time. Very frustrating.
Maybe I do it wrong, maybe we have to wait for iOS 11 for smooth file exchange. Don't know at the moment.