Its not unrelated, i did extensive benchmarking. That optimization is a trap, allowing too many low level implementations (3) once the index gets large.
OK. That's fine. I never liked that offset=0 specialization, i think back at that time we felt it might be a good idea. I don't know the issue number anymore.
You also removed the negative check in the new Multi implementation; I think this was done because of performance, too, right? I am not happy with that, because it no longer throws Exception if you try to access stuff off-slice. Maybe we can add an "assert" instead?