School early on has very little to do with acquiring knowledge (except for specifics in learning to read). It is about learning to wait your turn, not interrupt, share, listen, etc. Gifted kids need that as much (if not more) than most other kids.

I'm surprised to hear she is having behavior problems in a 4-year old classroom. I've known quite a few gifted kids (my own and others) and none have had problems in preschool. There should be enough flexibility and attention in any classroom to meet a kid where they are. If they are sitting doing worksheets and she is finishing before everyone else and acting up, then the curriculum is bad. It should really be very free-form and play-centric at this age.

If you'r on Facebook, check out Hoagies Gifted and Crushing Tall Poppies.