Question about "new" keyword and performance

I've read that we should avoid allocating memory at runtime. Does this apply to every type of variable? I know that I shouldn't use new to initialize reference class object at runtime. But what's about struct like Vector2 or Vector3? Should I avoid to create (using new) them at runtime too?

anytime you want to set any component of a transform you have to call new Vector3, directly in c sharp and under the hood in javascript. to quote trinity from the matrix, "Dodge this!"