count.rb

pw = nil
pc = 0
$stdin.each do |line|
  line.chomp!
  w, year, c1, c2 = line.split(/\t/)

  if not pw.nil? and pw != w
    puts "#{pw}\t#{pc}"
    pw = nil
  end

  c1 = c1.to_i

  if pw.nil?
    pw = w
    pc = c1
  else
    pc += c1
  end
end

if not pw.nil? 
  puts "#{pw}\t#{pc}"
end

count.rs

use std::io;

fn main() {
    let mut pw: String = String::new();
    let mut pc: int = 0;
    let mut started = false;
    
    for line in io::stdin().lock().lines() {
        let line = line.unwrap();
        let mut split = line.split_str("\t");
        let _w = split.next().unwrap();
        let w = String::from_str(_w);
        split.next();
        let _c:Option<int> = split.next().unwrap().parse();
        let c = _c.unwrap();

        if started && pw != w {
            println!("{}\t{}", pw, pc);
            started = false;
        }
        
        if !started {
            started = true;
            pw = w;
            pc = c;
        } else {
            pc += c;
        }
    }

    if started {
        println!("{}\t{}", pw, pc);
    }
}

Thank @awesomeintheory and @bstrie. Now my program written in #Rust very fast just by adding "--release" to cargo. ^^

Ruby

real 90m47.088s
user 94m15.470s
sys 1m20.872s

Rust

real 11m9.995s
user 13m12.904s
sys 0m59.891s