Efficient way of loading a textfile that is 30MB to a Textbox?

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VB

file-system

read

I am creating an antivirus program, my problem is,I need to load text file to my textbox in order to know if my antivirus detected a virus. It basically searches for the given string in the textbox and if it matches then it found a virus using the FIleSystemWatcher. The problem is it takes a lot of time to load and it consumes a lot of RAM, is there a way that I don't have to load the entire textfile to textbox, but to cache the textfile to memory that I my application can read it from there to detect a virus. OR maybe I can buid just Embed the TextFile to my Resourcces section and Read it from there? Heres my code:


Loading frm


Using reader As System.IO.StreamReader = New System.IO.StreamReader("Virusdatabase.txt")
VirusdatabaseTextbox.Text = reader.ReadToEnd()
End Using

FIlesystemwatcher code: Event Created

Try
            Me.OpenFileDialog1.FileName = ""
            Dim md5 As New MD5CryptoServiceProvider
            Dim f As New FileStream(e.FullPath, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite, &H2000)
            f = New FileStream(e.FullPath, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite, &H2000)
            md5.ComputeHash(f)
            Dim hash As Byte() = md5.Hash
            Dim buff As New StringBuilder
            Dim hashByte As Byte
            For Each hashByte In hash
                buff.Append(String.Format("{0:X2}", hashByte))
            Next
            f.Close()
            If VirusdatabaseTextbox.Text.Contains(buff.ToString) Then 'Heres the comparison string to detect a virus
                Me.OpenFileDialog1.FileName = e.FullPath
				MessageBox.Show("Virus Detected! FilePath: ")
            End If

        Catch exception1 As Exception
            ProjectData.SetProjectError(exception1)
            Dim ex As Exception = exception1
            ProjectData.ClearProjectError()
        End Try

Thank You