Excel macro taking longtime - excel

Question

I am using the below excel which takes longtime to complete.
Usually i will have 30k records in invoice sheet and GRN sheet.
Can anyone suggest me to complete this task in faster way?
Sub CheckReturn()
Dim LastInvRow As Long
Dim LastGRNRow As Long
Dim i As Integer
Dim j As Integer
Application.Calculation = xlManual
LastInvRow = Sheets("Invoice").Cells(Rows.Count, "A").End(xlUp).Row
LastGRNRow = Sheets("GRN").Cells(Rows.Count, "A").End(xlUp).Row
For i = 4 To LastInvRow
For j = 2 To LastGRNRow
If Sheets("GRN").Cells(j, 11).Value = "Customer Return" And _
Sheets("GRN").Cells(j, 3).Value = Sheets("Invoice").Cells(i, 7).Value And _
Sheets("GRN").Cells(j, 18).Value = Sheets("Invoice").Cells(i, 19).Value Then
Sheets("GRN").Cells(j, 34).Copy
Sheets("Invoice").Cells(i, 48).PasteSpecial Paste:=xlPasteValues
Sheets("GRN").Cells(j, 35).Copy
Sheets("Invoice").Cells(i, 49).PasteSpecial Paste:=xlPasteValues
Sheets("GRN").Cells(j, 36).Copy
Sheets("Invoice").Cells(i, 50).PasteSpecial Paste:=xlPasteValues
Exit For
End If
Next j
Next i
Application.Calculation = xlAutomatic
MsgBox "Completed - " & Now()
End Sub

Answer 1

I suggest to do direct transfer of data from one sheet to the other and turn off some applications to make it even fater. Try this one:
Sub CheckReturn()
Dim LastInvRow As Long
Dim LastGRNRow As Long
Dim i As Integer
Dim j As Integer
'turn applications off, to make the macro go faster
Application.ScreenUpdating = False
Application.EnableEvents = False
Application.Calculation = xlManual
LastInvRow = Sheets("Invoice").Cells(Rows.Count, "A").End(xlUp).Row
LastGRNRow = Sheets("GRN").Cells(Rows.Count, "A").End(xlUp).Row
For i = 4 To LastInvRow
For j = 2 To LastGRNRow
If Sheets("GRN").Cells(j, 11).Value = "Customer Return" And _
Sheets("GRN").Cells(j, 3).Value = Sheets("Invoice").Cells(i, 7).Value And _
Sheets("GRN").Cells(j, 18).Value = Sheets("Invoice").Cells(i, 19).Value Then
Sheets("GRN").Cells(j, 34).Copy = Sheets("Invoice").Cells(i, 48)
Sheets("GRN").Cells(j, 35).Copy = Sheets("Invoice").Cells(i, 49)
Sheets("GRN").Cells(j, 36) = Sheets("Invoice").Cells(i, 50)
Exit For
End If
Next j
Next i
Application.Calculation = xlAutomatic
MsgBox "Completed - " & Now()
'turn applications back on..
Application.ScreenUpdating = True
Application.EnableEvents = True
End Sub

Answer 2

This one should be a bit faster. Because you don´t get the values of a and b each time when the for j loop begins.
Sub CheckReturn()
Dim LastInvRow As Long
Dim LastGRNRow As Long
Dim i As Integer
Dim j As Integer
Application.Calculation = xlManual
LastInvRow = Sheets("Invoice").Cells(Rows.Count, "A").End(xlUp).Row
LastGRNRow = Sheets("GRN").Cells(Rows.Count, "A").End(xlUp).Row
For i = 4 To LastInvRow
a=Sheets("Invoice").Cells(i, 7).Value
b=Sheets("Invoice").Cells(i, 19).Value
c=Sheets("GRN").Cells(j, 34).Value
d=Sheets("GRN").Cells(j, 35).Value
e=Sheets("GRN").Cells(j, 36).Value
For j = 2 To LastGRNRow
If Sheets("GRN").Cells(j, 11).Value = "Customer Return" And _
Sheets("GRN").Cells(j, 3).Value = a And _
Sheets("GRN").Cells(j, 18).Value = b Then
Sheets("Invoice").Cells(i, 48).Value=c
Sheets("Invoice").Cells(i, 49).Value=d
Sheets("Invoice").Cells(i, 50).Value=e
Application.Statusbar= i*j*100/LastInvRow*LastGRNRow & "%"
Exit For
End If
Next j
Next i
Application.Calculation = xlAutomatic
MsgBox "Completed - " & Now()
End Sub
The statusbar will show you the progress of your task in %.