When you move between images it loads low res first then renders the full res version. This takes about 3 seconds, which might not sound like much but it’s a pretty long time. It does this even if you have 1:1 Previews generated. On top of that, when you move between images in the develop module, they load sharp (i.e. Full res) instantly for a split second, then they go low res for 3 seconds or so and then they go back full res. It feels really slow and clunky, so again, half baked but better than nothing.