It's perfect now, fast scrolling through hundreds of thumbs without any noticeable drop in FPS.
Also it just looks damn cool when the box thumb plays in sync with the background.
Fantastic, I'll add it as an option in Arcadeflow 6.0. Of course if you move away from a playing thumbnail and quickly back the sync effect will be lost because background animations don't fade out the same way as thumbnail animations. Maybe this can be added but I still think it's a bit overkill

What I meant is;
I have my SNES set as such, as I prefer everything to be keept with the rooms, for multiple reasons:
artwork flyer /home/.../RetroPie/roms/snes/assets/covers
artwork snap /home/.../RetroPie/roms/snes/assets/screenshots;/home/gregory/RetroPie/roms/snes/assets/videos
artwork title /home/.../RetroPie/roms/snes/assets/wheels
artwork video /home/.../RetroPie/roms/snes/assets/videos
yet, If the logos aren't in the:
/home/.../.attract/scraper/Super Nintendo Entertainment System/wheel
the skin won't display them [ the logos above the snaps ]
In this case the issue is that your artwork for wheels is named "title", while Arcadeflow expects wheel artwork to be in the wheel category. So in the options above just add something like:
artwork wheel /home/.../RetroPie/roms/snes/assets/wheels
and it should work.
One other thing. I had to disable frosted glass effect for Displays List as it introduces noticeable delay when opening it, without it it's instant [ AMDVEGA APU, SSD PCIe disk ] and I'm assuming it's the reason why random screenshots kept appearing in my attract config folder
Irregardless of that there's a bug when Display List is set as first to open in Attract, it will open without any background or black one.
Frosted glass is a dirty trick, it saves a screenshot and reload it back to apply effects, it seems there's some slowdown when your Attract Mode saves this screenshot. If everything works fine Arcadeflow will purge all the spurious screenshots so you should not find them in your folder, unless AF crashes of course

And the black background always happens when you enter the menu after coming back from attract mode options screen (which is black). I can't find a way to get rid of that, seems intrinsic in the way Attract Mode redraw the display.
And the last one, attract mode is incredibly zoomed to the middle, it shows something like 16% of the snap? In case of the games which have dividers like Super Mario Kart from SNES, all it shows is a dvider [ 1920 x1080 res ]
Can you paste a screenshot of the issue?