DD6's violin teacher has a group of children that are very, very good and perform together from time to time.
It seems to be a requirement to join the performing group if your child takes lessons.
DD6 was very adverse to the idea, and I told the teacher that we thought it was a very bad idea due to her personality. The teacher has been very understanding and so she doesn't ever perform.
I'm not a big fan, but it depends on the child. Some children seem to absolutely thrive when given the opportunity to perform, public or other.