I would hope that they aren't doing that calculation for every sprite every frame. It strikes me that most of the sprites and probably most of the light source

I would hope that they aren't doing that calculation for every sprite every frame. It strikes me that most of the sprites and probably most of the light sources are static, so most of the information could be precalculated and cached, which would leave just the moving sprites and lights. I would probably look at some kind of spatial partioning and marking sections dirty to prune things further. If it turned out to be significant enough that it was hurting framerate, anyway.