My main is a Emp/Psi but she's buffed up on her Empathy side. The Psi side is lacking in awesome enchancements but she can pack a fair punch, Psychic Tornado is actually my personal fave Psi skill, what about it makes you say it's slow? If you mean the animation, then yes it is a little slow, I often wonder if my girl will get her arms up in the air to launch the tornado or run out of steam before she gets there lol. However I must agree with BlissfulChaos, I probably don't notice it too much since I am so busy healing and buffing.
I also like Psychic Tornado, 'cause of the DOT effect, while it's doing damage I can go back to healing/buffing, and since it's a pretty fast recharge I get to use it again and then go back to healing and the circle begins!