While loop causes the app to go slow? Any idea why? - vb.net

Question

I have a simple code that looks up a text file, reads the line of text, splits the string by semi-colons and then posts the results.
After it has done this, I have created a really simple while loop to waste 10 seconds before going for it again.... here is the code:
Private Sub checkTemps()
While Abort = False
Try
fileReader = New StreamReader(directory.Text & "currentTemp.dat")
rawData = fileReader.ReadLine()
fileReader.Close()
Dim dataArray() As String
dataArray = rawData.Split(";")
updateOutput("1", dataArray(0), dataArray(1))
updateOutput("2", dataArray(2), dataArray(3))
updateOutput("3", dataArray(4), dataArray(5))
updateOutput("4", dataArray(6), dataArray(7))
stpWatch.Start()
While stpWatch.Elapsed.Seconds < 10 And Abort = False
pollInterval(stpWatch.ElapsedMilliseconds)
End While
stpWatch.Stop()
stpWatch.Reset()
Catch ex As Exception
msgbox("oops!")
End Try
End While
closeOnAbort()
End Sub
But when it gets to the "time-wasting" loop - it seems to slow the whole application down? And I can't work out why!
So a couple of questions... is there a better way to do all this? and second - can anyone spot a problem?
All the other commands seem to run fine - there isn't much else to this app. I have another program that updates the dat file with the values, this is simply a client side app to output the temperatures.
Any help would be appreciated.
Andrew
More info:
I should explain what the pollInterval sub does!
Private Delegate Sub pollIntervalDelegate(ByVal value As Integer)
Private Sub pollInterval(ByVal value As Integer)
If Me.InvokeRequired Then
Dim upbd As New pollIntervalDelegate(AddressOf pollInterval)
Me.Invoke(upbd, New Object() {value})
Else
ProgressBar1.Value = value
End If
End Sub

Answer 1

Your loop is a very tight loop continually calling pollInterval. This will tie up the application until the loop condition is met.
You should use the Sleep method to pause this thread for the required amount of time.
If you want to show the progress (as per your update) you could put the Sleep into the loop and sleep for 1 second (or half a second?) at a time:
While stpWatch.Elapsed.Seconds < 10 And Abort = False
Sleep(1000) <-- NOT 100% sure of the syntax here,
but the time is specified in milliseconds
pollInterval(stpWatch.ElapsedMilliseconds)
End While

Answer 2

You should go with
System.Threading.Thread.Sleep(TimeSpan.FromSeconds(10).TotalMilliseconds);