Is .Net 4 slower than .Net 3.5?

See more:

.NET

.NET4

Hi all,

I was testing the runtime of some calculations with VS 2008 and .Net 3.5. Somehow unsatisfied with the result I thought I startup VS 2010 Express and try my luck with the Parallel Extensions. The first thing I've done was to copy the code to a new VS 2010 project and rerun my test. To my surprise it was by far slower than in .Net 3.5 (66 seconds, 38 seconds). I ran both tests with release builds outside the debugger. This really puzzles me as I somehow can't believe the performance drop is so great.

Here is my test code:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace SaTest
{
    class Program
    {
        struct Structure
        {
            public float X;
            public float Y;
        }


        static void Main(string[] args)
        {
            var l = new Structure[2000000];
            var r = new Random();
            for (int i = 0; i < l.Length; i++)
            {
                l[i].X = (float)(r.NextDouble() * 1000000);
                l[i].Y = (float)(r.NextDouble() * 1000000);
            }

            int counter = 0;
            double dist = 2000;
            double distSquare = dist * dist;

            var sw = new Stopwatch();
            sw.Start();
            for (int i = 0; i < l.Length; i++)
            {
                for (int j = 0; j < 2000; j++)
                {
                    double tx = l[i].X - l[j].X;
                    double ty = l[i].Y - l[j].Y;
                    if (tx * tx + ty * ty <= distSquare)
                        //if (Math.Sqrt(tx * tx + ty * ty) <= dist)
                        counter++;
                }
            }
            sw.Stop();
            Console.WriteLine(counter);
            Console.WriteLine(sw.Elapsed);
            Console.ReadLine();
        }
    }
}

Has anyone made similar experiences? Or is something weird wrong with my code? I would appreciate if anyone could test this and tell me if my results are reproducable.