The view options are what killed it in the end.
The thumbnails issue was just me looking at the sausage and like "ugh, I wouldn't have done that."
It's always a tradeoff between time and work. I would have done a sliding window around the current screen, but then you might have placeholders. Maybe it should do low-res first and generated hi-res thumbnails 3 pages out while scrolling. But that's a lot of work for the 10% case.
What I want is aperture back, with all the fun AI stuff and using Affinity for photo editing (which I have anyway). I'll add that to my queue of projects I guess.