little Benchmark

Is there any reason for the X variable to be an integer? It works faster when it is declared as Double, as the Y variable, this way, the test makes much more sense to me.

I've converted the code to Visual Basic .net and it took 9 seconds with the debug on, and 93 milliseconds running with the program built and no debuger present. So I supose you tested C# from the visual studio IDE over a debug build, try it over a release build directly from windows, and I supose you'll get a much better performance.

Sample code (the program has a form with a button and a textbox)

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Anzahl As Integer, Iterationen As Integer, EndTime As Long
        Dim StartTime As Long
        Dim i As Long
        Dim DauerMsec As DateTime
        Dim x As Double, y As Double
        Anzahl = 10000
        Iterationen = ((Anzahl - 1) * Anzahl / 2)

        EndTime = Now.Ticks

        For i = 0 To Iterationen
            y = Math.Sin(i)
            x = Math.Cos(y)
            x = x * y
        Next
        StartTime = Now.Ticks

        DauerMsec = New DateTime(StartTime - EndTime)

        SPrint("Anzahl: " & Anzahl)
        SPrint("Iterationen: " & Iterationen)
        SPrint("Time: " & DauerMsec.ToString & " " & DauerMsec.Millisecond)

    End Sub
    Sub SPrint(ByVal Str As String)
        Me.TextBox1.AppendText(Str & Chr(13) & Chr(10))
    End Sub
End Class

(I thought .net would be slower but oh surprise!)