I'm still tiiiiiired... my brain is nearly HS.
I thought that the arrow I posted yesterday would play at 24 fps. It does it correctly on Chrome but on Safari, it is slower.
I searched the speed and it seems if the gif is running at 15 fps or less, it plays good but if the gif is running at more, it's kept at 15. I've to check that. But it is for tomorrow. I give up for today.
Pic of the day:

animated arrow with 15 frames