For Android most of the lag (IME) is artificial. To disable it, enable the Developer Options panel, and set "Window animation scale", "Transition animation scale", and "Animator duration scale" to off (or minimum value if you still want some animation). Suddenly it's much more responsive!

Totally shit design. And could still have lower input lag. But instead of reducing it they added slow animations to try to hide it, which makes it take even longer!