It is remarkably unhelpful to describe it as enthusiasm.
And it is certainly not something to be curbed.
IQ doesn't measure a fixed quantity - it measures rarity. So most are round about a 100. And there are less at 80 and 120. And at 40 and 160, there are very few of us indeed.
So one of our biggest problems is a social problem. Imagine what it is like to be 100 talking to a 40, well it is the same for 160 talking to a 100.
I think with your talk of enthusiasm and curbing you would fail any gifted student in your class.
I think you owe it to any gifted student you come across to learn what giftedness is and how to nourish it.
You can do this at Hoagies' Gifted Education Page: Parenting and educating gifted children