[@thewizardguy] In her Ten Tails form yeah. However when she was in her perfect form Black Zetsu clearly said she was 'low' on chakra after spamming some stuff. She didn't seem tired. It was all just very confusing at that final part. 

Yes we are in agreement. 

As for her reaction time, I just find it very difficult to evaluate in the final arc of Naruto. She's clearly superior to Madara, who in turn could manhandle someone as fast as Minato. I think most who watched Shippuden know how absurd his speed and reaction time were.