Extracting Specific Text from a string is slow

[ozoner]

I have a text file I'm trying to pull specific data from to make a report in excel and am wanting to know if my code can be improved or if I have something wrong. If it's apparent to anyone that I should be doing something else could you tell me please. This code does work but, very slow. These reports take up to 20 minutes for about 100 files so I am wanting to decrease the time somehow. I have attached the whole sub in a text file, it's about 900 lines long so don't think I should post all of it. This is one part that seems to take the longest:

Partial code that reads the text into a string, then each line is read to find whether it holds the data or not. Inside this while loop, I am checking numerous lines to see what they hold and extract specific items. First I verify it's a interface by checking for "line protocol".

Dim str As StreamReader = File.OpenText(filefound)
                    While (str.Peek <> -1)
                        If txtLine.Contains("line protocol") = True Then 'Found an interface,

'Then a snippet that grabs a few more things, these three items are always on a single line. Then I place into excel cells.

'Get MTU, BW and DLY
                        If txtLine.Contains("MTU") = True And txtLine.Contains("BW") = True And txtLine.Contains("DLY") = True Then
                            PosX = txtLine.IndexOf("MTU") + 4                           ' MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, 
                            PosY = txtLine.IndexOf("bytes,")                            '     ^   ^
                            PosY = PosY - PosX
                            MTU = txtLine.Substring(PosX, PosY)
                            oSheet.Cells(oRow, 6).value = MTU

                            PosX = txtLine.IndexOf("BW", 1) + 3                            'MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, 
                            PosY = txtLine.IndexOf("bit", 1)
                            PosY = PosY - PosX - 2
                            BW = txtLine.Substring(PosX, PosY)
                            oSheet.Cells(oRow, 7).value = BW

                            PosX = txtLine.IndexOf("DLY") + 3
                            PosY = txtLine.IndexOf("usec")
                            DLY = txtLine.Substring(PosX, PosY - PosX)

                            oSheet.Cells(oRow, 8).value = DLY
                        End If

Here is another snippet that grabs a single value from within this same readline loop.

'Get Description
                        If txtLine.Contains("Description") = True Then
                            txtLine.Trim()
                            Desc = txtLine.Replace("Description", "")
                            Desc = Trim(Desc)
                            Desc.Replace(":", "")
                            oSheet.Cells(oRow, 5).Value = Desc.Replace(":", "")
                        End If

Very appreciative of any help/suggestions. Thanks.