Originally Posted by
neveron
It's mostly the thing where she has a 27% NP charge skill. Her Arts card is ever-so-slightly better at NP generation than Jack's (one hit times 2.15% vs. two hits times 1.07% or 2.14%ish), and her Quick cards having just two hits rather than Jack's five means that she gets less than 40% of the stars and also, well, ~4.30% NP on her first Quick card vs. Jack's ~5.35%.
Note that exact percentages depend on chains, card position, crits, and overkill.
So yeah, it's mostly the 27% charge from using Vampirism every six turns. She can churn that thing out pretty quickly, though.