Why does a loop go faster if you add condition in it ?

Question

The other day I 've added a condition within a loop and I expected the code to go slower but it actually went faster !
You add a condition and the loop goes faster ... that's not logical for me and I'd like to understand it so if you have an explanation please post it below.
I've also discovered that this anomality happens only when the code is within a try-catch block.
I've reproduced the phenomenon with this little example class.
Try to comment and uncomment the only condition within the loop and to do the same for the exception. If you use the java 5 you should see similar results (haven't try with other JVM)
public class Test {
    public Test() {}
    public static void main(String[] args) {
        Test t = new Test();
        t.execute();
     * With try-catch :
     *    with condition           ms = 2641  (faster)
     *    without condition        ms = 3047 
     * Without try-catch :
     *    with condition           ms = 2625 
     *    without condition        ms = 2515  (faster)
    public void execute() {
        try {
            int c = 0;
            long t1 = System.currentTimeMillis();
            for (int i = 0; i < 1000000000; i++) {
                c++;
                if (c == 0) {
                    c--;
            System.out.println(" ms = " + (System.currentTimeMillis() - t1) + "  " + c);
        } catch (Exception e) {
            e.printStackTrace();
}

Answer 1

The other day I 've added a condition within a loop
and I expected the code to go slower but it actually
went faster ! The try block has absolutely nothing to do with method speed (unless of course you throw exceptions.)
Excluding that you ran one test with a condition where it was faster and one where it was slower.
And what exactly else was running on your computer when you did this? A virus checker? Scheduled tasks? Editor? IDE? Database? Services (like network stacks?) All of those take time from the cpu. And if even one of them did anything at all when your test was running then it will change the results.