Perf of struct w/ string vs class w/ string

QUESTION: Are my assumptions correct and Class is a better choice for this kind of a situation or is it still more beneficial and faster to use Struct?

Is it more efficient to use Class instead of Struct when I pass an object as a parameter and want to avoid allocating memory for StringValue?

It is more efficient to use Struct instead of Class when you pass an object as a parameter and want to avoid allocating memory for StringValue.