Function domain_points 

fn domain_points<F: FftField>(domain: Radix2EvaluationDomain<F>) -> Vec<F>

The points of domain (g^0, g^1, …), computed in parallel. Each chunk seeds its first power with a single exponentiation and then walks a running product, so the work is O(n) multiplications spread across the cores with only one pow per chunk of overhead. For domains smaller than the chunk size this is a single sequential chunk, so the parallelism never dominates.