Not only that but she could not gain Life Energy from those she killed there since she could not take the time to activate her chant and hand signs.
Even if she was able to complete her chant in the middle of a fight or toward the end of it, doing that in front of a live audience would not go unnoticed.
It was a dangerous action to take since it risked exposing the existence of Balancers which was taboo in the world of Balancers.
Not only was it dangerous in that way but there was always a risk of there being a Watcher or Balancer among the staff or the audience that could identify her as being one of them.
If she was seen abusing her powers against ordinary humans while risking exposing her abilities too then that was asking for a lot of trouble.