LSi stands for "line speed improved" and I would agree that the action is fast, so the rod feels light and zippy. But it's not one of those "fast for the sake of fast" rods. I never have been a fan of "casting" fly rods, because I like to use fly rods for fishing, not necessarily casting. And to me, a good fishing rod is one that can punch a decent wind cast into a stiff breeze, but also perform gently as you lift and mend, roll cast, and all of that. I found, over the course of this summer's fishing in both small creeks and on bigger rivers, that I kept picking up the LSi on my way out the door because it was versatile, and it was the rod I felt comfortable with.