Standard stdout on windows is really slow. Instead, getting a handle to the CONOUT$ and writing to it, can increase the speed a LOT.

cargo.toml

[package]
name = "rustfastcmd"
version = "0.1.0"
authors = ["Pablo Ordoñez <pabloo84@gmail.com>"]

[dependencies]

[target.'cfg(windows)'.dependencies]
winapi = { version = "0.3", features = ["winuser", "wincon", "fileapi", "handleapi"] }

fast_console.rs

extern crate winapi;

use winapi::um::fileapi::CreateFileW;
use winapi::um::handleapi::CloseHandle;
use winapi::um::wincon::{WriteConsoleOutputCharacterW, COORD};

use std::ptr::null_mut;
use std::time::{Duration, Instant};

fn get_wstring(msg: &str) -> Vec<u16> {
    use std::ffi::OsStr;
    use std::iter::once;
    use std::os::windows::ffi::OsStrExt;

    OsStr::new(msg).encode_wide().chain(once(0)).collect()
}

fn main() {
    let console_handle = unsafe {
        CreateFileW(
            get_wstring("CONOUT$").as_ptr(),
            0x40000000,
            2,
            null_mut(),
            3,
            0,
            null_mut(),
        )
    };

    println!("{:?}", console_handle);

    let raw_message = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
    let mut fps_text = String::from("FPS: 0") + &raw_message;
    let mut chars: u32 = 0;
    let mut fps = 0;
    let mut duration = Duration::from_micros(0);

    loop {
        fps += 1;
        let now = Instant::now();

        unsafe {
            WriteConsoleOutputCharacterW(
                console_handle,
                get_wstring(&fps_text).as_ptr(),
                raw_message.len() as u32,
                COORD { X: 0, Y: 0 },
                &mut chars as *mut u32,
            )
        };

        duration += now.elapsed();

        if duration.as_secs() > 1 {
            duration = Duration::from_micros(0);
            fps_text = String::from("FPS: ") + &fps.to_string() + &raw_message;
            fps = 0;
        }
    }

    unsafe { CloseHandle(console_handle) };
}