I'm currently playing with multithreading in vb.net and I can run one thread with no problem. If I try to run two threads, it seems to run slowly for some strange reason. I don't know how to expain it. Maybe the code i'm using will help(wo/ form code):

Code:
Public Class Form1
    Inherits System.Windows.Forms.Form
    Dim t1 As System.Threading.Thread
    Dim t2 As System.Threading.Thread
#Region " Windows Form Designer generated code "

    Private Sub BackgroundProcess1()
        '//setting up the first subroutine that will run in thread
        Dim i As Integer = 1

        Do While True
            TextBox1.Text = "Iterations: " & i
            i += 1
        Loop
    End Sub
    Private Sub BackgroundProcess2()
        '//setting up the second subroutine that will run in thread
        Dim i2 As Integer = 1

        Do While True
            TextBox2.Text = "Iterations: " & i2
            i2 += 1
        Loop
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        '//assigning subroutine to the thread and starting thread
        t1 = New System.Threading.Thread(AddressOf Me.BackgroundProcess1)
        t2 = New System.Threading.Thread(AddressOf Me.BackgroundProcess2)
        t1.Start()
        t2.Start()
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        '//setting up button that will stop and start thread
        If Button1.Text = "Stop" Then
            t1.Suspend()
            t2.Suspend()
            Button1.Text = "Start"
        ElseIf Button1.Text = "Start" Then
            t1.Resume()
            t2.Resume()
            Button1.Text = "Stop"
        End If
    End Sub
End Class