Excel テキストファイル読み込みを　TextStream で劇的に高速化した

条件：文字数　85万文字　

before ４分　after 0.4秒

当初の１行処理文字数　85万　で　４分

Public Function ReadTextFile(ByVal sFilePath As String, _
ByRef strResult As String, _
Optional blnVBCRLF As Boolean = False) As Boolean
 
　Dim buf As String, Cnt As Long
　On Error GoTo myErr
　Cnt = 0
　Open sFilePath For Input As #1'"C:\Work\Sample.txt"
　Do Until EOF(1)'EOFまで１行ずつ転記する
　Line Input #1, buf
　If blnVBCRLF = True Then
　　strResult = strResult & buf & vbCrLf
　Else
　　strResult = strResult & buf
　End If
　Cnt = Cnt + 1
　If Cnt Mod 5000 = 0 Then
 
　　Sleep 25
　　DoEvents
　　Sleep 25
　End If
　Loop
　Close #1'注意：Closeしないと　次回からOpen　できない
MyExit:
　ReadTextFile = True
　Exit Function
myErr:
　ReadTextFile = False
End Function

TextStream　で読み込み　　同条件 85万文字で0.4秒！

Public Function ReadTextFileStream(ByVal sFilePath As String, _
ByRef strResult As String) As Boolean
　Dim buf As String
　With CreateObject("Scripting.FileSystemObject")
　　With .GetFile(sFilePath).OpenAsTextStream
　　　buf = .ReadAll
　　　.Close
　　End With
　End With
MyExit:
　strResult = buf
　ReadTextFileStream = True
Exit Function
　myErr:
　ReadTextFileStream = False
End Function