You're worrying about a constant slowdown (6x) on a constant operation (constructing a dictionary with a fixed number of items). In terms of computational compl

You're worrying about a constant slowdown (6x) on a constant operation (constructing a dictionary with a fixed number of items). In terms of computational complexity, that amounts to two times a negligible constant, i.e., nothing. I think the reason for having set literals is not performance but completeness and prettier syntax.