Tsubaki's isn't a fast fall, since j.D floats her in the air, so it's kind of a really slow-falling glide.
Be very patient in this matchup, using B specials for projectile invincibility is a very inconsistent option that often results in you getting counterhit and comboed. Generally only charge when you are positive he won't hit you. I generally play this matchup with very little charge, or even no charge. Getting in and preventing the lambda player from zoning you out takes priority.