Macro Runtime Suddenly Slow

Question

I have an identical piece of code which was running nearly instantly in an previous iteration which now takes about 5 minutes to run. I edited other parts of the code, but whenever I break the code within that 5 minute period of time, it is working through this sub.

Sub cleanup()

For i = 2 To 100000

'exits loop when it reaches a blank cell
If IsEmpty(Cells(i, 1)) = True Then Exit For

' formats for blanks
If Cells(i, 1) = Cells(i - 1, 1) Then
    For j = 4 To 15
        If IsEmpty(Cells(i - 1, j)) = True Then
        Cells(i - 1, j) = Cells(i, j)
        End If
    Next j
    Rows(i).Delete
    i = i - 1
End If

Next i

End Sub

I've tried disabling events and screen updating etc, but can't figure it out. Keep in mind this used to run literally instantly and I only changed other functions in my code since those changes. Not sure what to do. Thanks!

**

The other part which is very weird is when I run the macro again (after all the rows are deleted) it still takes a very long time. In the above macro, the second time through it should never even enter the first conditional but it still takes a long time.

**

Answer 1

Sub cleanup()

For i = Range("A" & Rows.Count).End(xlUp).Row + To 2 step -1

    If Cells(i, 1) = Cells(i - 1, 1) Then
        For j = 4 To 15
            If IsEmpty(Cells(i - 1, j)) Then Cells(i - 1, j) = Cells(i, j)
        Next j
        If CellArray Is Nothing Then
            Set CellArray = Rows(i)
        Else
            Set CellArray = Union(CellArray, Rows(i))
        End If
    End If
Next i

CellArray.Delete

End Sub

Answer 2

I may be oversimplifying your task, but if you use the built-in counta function within Excel, I think it would be very efficient at determining if a row had values in it or not:

If Excel.WorksheetFunction.CountA(rw.EntireRow) = 0 Then
  rw.Delete
End If

Of course, this looks at the entire row and you probably want to bound that to columns 4 - 15 (or whatever you showed above).

Also, I think @Marcucciboy2 made a good point, and I would start from the bottom up.

If you really wanted to make this hum, you could probably define these in a range context (ie 1:4,5:7 etc) and delete the entire collection of rows at one time.

Answer 3

In the excel, if you can avoid the for loops, its very slow. For example: my work i use 7000x746x3 rows, and its running about 15 minutes(i5 7300u,but not mucher faster on desktop 7770. Maybe little optimazition here: https://www.ozgrid.com/VBA/SpeedingUpVBACode.htm or use foreach. And if you use for you can count the row/column. Example row count:

LastRow = Worksheets("Sheet").Cells(Worksheets("Sheet").Rows.Count, "A").End(xlUp).Row