code more efficient for generic containers when they contain valuestype

[puzzlecracker]

Allegedly, they are more efficient than their non-generic counterparts
because they avoid boxing.

How is it possible to avoid boxing whenever generic code is used?
Wouldn't autoboxing still require whenever open type is expended and
used for value types as in the example below:

List<intlist=ne w List<int>();

list.Add(5); //Wouldn't this auto-box into Integer?

Thanks