RUST code optimisation

Hi, I'm beginning with RUST, and I was comparing some code written in C# to see if it performs well. I find that the RUST version is slower, but I don't know if I made some obvious mistakes. I tried unsuccessfully some optimisation (like use iterators instead of the for loop).
Any advice to speed up the RUST version without multithreading?

C# → 20 sec :

  var random = new Random();
  const int count = 4096;
  double[] data = (from i in Enumerable.Range(0,count) select (double)random.NextDouble()).ToArray();

var watch = new System.Diagnostics.Stopwatch();

watch.Start();
double[] output = new double[count];
for(int id = 0;id < count;id++) {
    double value = data[id];
    for(int i = 0;i < 3000000;i++) {
        if(value > 0.5) {
            value *= 0.99;
        } else {
            value *= 1.01;
        }
    }
    output[id] = value;
}
watch.Stop();
Console.WriteLine($"Execution Time: {watch.Elapsed.TotalSeconds} sec");
Console.WriteLine($"{output[23]}");

RUST → 41 seconds

  use std::time::Instant;

  use rand::Rng;

  const COUNT: usize = 4096;

  fn main() {
    let mut data = vec![0.0f32; COUNT];
    let mut output = vec![0.0f32; data.len()];

    let mut rng = rand::thread_rng();
    for val in data.iter_mut() {
        *val = rng.gen();
    }

    let now = Instant::now();
    output.iter_mut().zip(data).for_each(
    |(value, input)|
        {
             *value = input;
            (0..3000000).into_iter().for_each(|_|
                if *value > 0.5f32 {
                    *value *= 0.99f32;
                } else {
                    *value *= 1.01f32;
                }
            );
        }
    );

    let elapsed = now.elapsed();
    println!("Elapsed: {} seconds", elapsed.as_secs());
    println!("{}", output[23]);
}