Compile with `rustc -C opt-level=3 -C target-cpu=native -C lto -C panic=abort split.rs -o splitrs`

split.rs

use std::io::{self, BufRead, BufReader, Write};
use std::time::Instant;

fn main() {
    // Obtain a buffered handle to standard input
    let stdin = io::stdin();
    let mut stdin = BufReader::new(stdin.lock());

    // Mark the current time for a later duration comparison.
    let start = Instant::now();
    
    // Obtain the number of words and characters in each word
    let (mut count, mut num_words, mut num_chars) = (0, 0, 0);
    let mut line = Vec::with_capacity(128);
    while stdin.read_until(b'\n', &mut line).unwrap_or(0) > 0 {
        for word in line.split(|&x| x == b' ') {
            num_words += 1;
            num_chars += word.len();
        }
        line.clear();
        count += 1;
    }

    // Obtain the duration of the computation.
    let duration = Instant::now().duration_since(start);
    
    let mut stderr = io::stderr();
    let _ = writeln!(stderr, "Rust   : Saw {} lines ({} words/{} chars) in {}.{} seconds.",
        count, num_words, num_chars, duration.as_secs(), duration.subsec_nanos());
}