>>531591728
It's a combination of many things
>high initial guage + hint rate + all events give gauge = earlier rainbows
>high training% gives big stat gains even before rainbows
>high specialty lets her appear in speed training more than all other cards
>some mood bonus to top it off (it does basically nothing)
What you also need to take note of is how much she boosts your power from speed rainbows. This is what really makes her broken, since you can get high power without running a single power card.