Why 64 bits app with double is slower than my 32 bits app?

 

Hello, I execute this simple program on win7 and win8 in 32 bits and 64bits
why the 64 bits version is significantly slower than 32 bits? It is 3 times slower on double and float...
Am I doing something wrong?

Thanks
w

Win 8 (64 bits) , app compile in 32 bits:
double: milliseconds: 1281.3019
float: milliseconds: 1284.5283

Win 8 (64 bits), app compile in 64 bits:
double: milliseconds: 3453.2643
float: milliseconds: 3484.5163

        public static void doubleTest(int loop)
        {
            Console.Write("double: ");
            for (int i = 0; i < loop; i++)
            {
                double a = 1000, b = 45, c = 12000, d = 2, e = 7, f = 1024;
                a = Math.Sin(a);
                b = Math.Asin(b);
                c = Math.Sqrt(c);
                d = d + d - d + d;
                e = e * e + e * e;
                f = f / f / f / f / f;
            }
        }

        public static void floatTest(int loop)
        {
            Console.Write("float: ");
            for (int i = 0; i < loop; i++)
            {
                float a = 1000, b = 45, c = 12000, d = 2, e = 7, f = 1024;
                a = (float)Math.Sin(a);
                b = (float)Math.Asin(b);
                c = (float)Math.Sqrt(c);
                d = d + d - d + d;
                e = e * e + e * e;
                f = f / f / f / f / f;
            }
        }

        static void Main(string[] args)
        {
            DateTime time = DateTime.Now;
            doubleTest(5 * 10000000);
            Console.WriteLine("milliseconds: " + (DateTime.Now - time).TotalMilliseconds);

            time = DateTime.Now;
            floatTest(5 * 10000000);
            Console.WriteLine("milliseconds: " + (DateTime.Now - time).TotalMilliseconds);

        }

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w.