Máš to nějaké pomalé... Java 1.6.0, stará E6300.

public class Test {

    public static void main(String[] args) {
            long timeBefore = System.nanoTime();
            double i = Math.pow(10, 9);
            long retyped = (long) i;

            while (retyped > 0) {
                retyped = retyped - 1;
            }

            long timeAfter = System.nanoTime();
            long time = (timeAfter - timeBefore) / 1000000;
            System.out.println(time + " ms");
        }
}

2536 ms
2534 ms
2532 ms
2543 ms
2537 ms
2535 ms....atd.