dyn vs impl rust bench

bench.rs

use criterion::{criterion_group, criterion_main, Criterion};
use pprof::criterion::{Output, PProfProfiler};

// Type your code here, or load an example.
pub fn square<'a, I: IntoIterator<Item = &'a i32>>(
    vals: I,
) -> impl Iterator<Item = (&'a i32, i32)> {
    vals.into_iter().map(|v| (v, v * v))
}

pub fn sum_squared<'a, I: IntoIterator<Item = &'a i32>>(vals: I) -> i32 {
    square(vals).map(|(_, sq)| sq).sum()
}

pub fn square_dyn<'a, I: IntoIterator<Item = &'a i32> + 'a>(
    vals: I,
) -> Box<dyn Iterator<Item = (&'a i32, i32)> + 'a> {
    Box::new(vals.into_iter().map(|v| (v, v * v)))
}

pub fn sum_squared_dyn<'a, I: IntoIterator<Item = &'a i32> + 'a>(vals: I) -> i32 {
    square_dyn(vals).map(|(_, sq)| sq).sum()
}

const NUM_ROWS: i32 = 4096;

pub fn criterion_benchmark(c: &mut Criterion) {
    let data: Vec<i32> = (0..NUM_ROWS).collect();

    c.bench_function("impl", |b| b.iter(|| sum_squared(&data)));
    c.bench_function("dyn", |b| b.iter(|| sum_squared_dyn(&data)));
}

criterion_group! {
    name = benches;
    config = Criterion::default().with_profiler(PProfProfiler::new(100, Output::Flamegraph(None)));
    targets = criterion_benchmark
}
criterion_main!(benches);