Actually many reasons for a GA, but that is not the "Lion Air way" fast landings outside the TDZ that float are the norm.
I actually got that information out of the Boeing reps mouth after they had been looking at the flight quality assurance data....
I don't have that aircraft in my Lido/takeoff but I had been informed by others that the perf would not of been legally met for that landing. (I am informed that at the time of landing the runway would of actually been contaminated with standing water) easy to understand as the runways are not level and not groved... Thus easy to see how these situations arise!
PT6A