How much impact on performance does Future have compared to compatibility?

(not sure if this is in the right category)

I want to design a game that looks really good but also runs very well on low-end devices.

I believe one of the things that make a game look good is the future lighting.

I’ve heard it’s more intensive that the other lighting engines, but by how much? Would the different in performance be noticeable on low-end devices?

Dont even compare Future to compatibility, it’s the distance between china to our neighbour galaxy. If you want the best possible look without sacrificing much peformance then use shadowmap. However, if your map use many light sources then using shadowmap will be much worse than future visual wise.