Convert Row To Multiple Columns

I am work a worksheet that contain the data like that
A B
NUM1 Jene,Joly
NUM2 Jene,Selo,Diff
MUM3 Tino,Selo
………………
this worksheet has over 1,000 data.
i want get the result in sheet2 as below:
A B
NUM1 Jene
NUM1 Joly
NUM2 Jene
………………
i write the code
[PHP]Sub test()
Dim i As Integer
Dim arr() As String
Application. ScreenUpdating = False
On Error Resume Next
For i = 1 To Cells(Rows.Count, 1).End(xlUp).Row
arr = Split(Cells(i,2), ",")
For J = 0 To UBound(arr)
With Worksheets(2)
LASTROW = .Cells(Rows.Count, 2).End(xlUp).Row + 1
.Cells(LASTROW, 1) = Cells(i, 1)
.Cells(LASTROW, 2) = arr(J)
End With
Next J
Next i
Erase arr
Application.ScreenUpdating = True
End Sub
[/PHP]

the defult of this code is that it will take long time to get the result.so,i want to know how to make the code run fast.