Improve performance in Excel using VBA? - excel

Question

We have a single formula which we are coping to over to a defined range of over 250'000 cells. The performance of Excel clearly takes a hit. Is there a way to improve the performance by using VBA?
The formula returns either 0 or 1 as a value to the cell depending on 4 criteria. The Excel formula is:
=IF(NOT(ISTEXT($B9)),"",IF((L$5=""),"",IF(AND(M$5>MIN($G9,$H9),L$5<MAX($G9,$H9)),1,0)))
Thanks for your help !

Answer 1

Something like this could be an alternative to 250,000 rows of formulas. As stated in the comments, this still would take some time given the size of the data set. I ran a test with a sheet that just had the necessary cells populated with 249,488 rows and the code took 12 seconds to run. With more data in the sheet I anticipate it taking longer than that.
That said this will reduce the memory of your file significantly since there won't be any formulas:
Sub Run()
Dim i As Long 'Row number for loop
Dim lRow As Long 'Last row of data set
Dim ms As Worksheet
Set ms = Sheets("Sheet1") 'Change to whatever sheet you need this in
With ms
If .Cells(5, 12).Value = "" Then
MsgBox "Please enter a value in Cell L5 before proceeding."
Else
lRow = .Cells(.Rows.Count, 2).End(xlUp).Row 'This is assuming Column B is populated in full to the bottom of the data set
For i = 9 To lRow 'This is assuming you will be starting the calculation in row 9
If IsNumeric(.Cells(i, 2).Value) = False And .Cells(i, 2).Value <> "" Then 'Ensuring Column B is text and not blank
If .Cells(5, 12).Value < WorksheetFunction.Max(.Cells(i, 7).Value, .Cells(i, 8).Value) And .Cells(5, 13).Value > WorksheetFunction.Min(.Cells(i, 7).Value, .Cells(i, 8).Value) Then
.Cells(i, 1).Value = 1 'Assuming you want the 0 or 1 in Column A
Else
.Cells(i, 1).Value = 0 'Assuming you want the 0 or 1 in Column A
End If
End If
Next i
End If
End With
End Sub
EDIT
Per Cornintern's awesome suggestion, I've rewritten this to use arrays instead of looping through the entire range. This now takes less than 2 seconds:
Sub Run()
Dim i As Long 'Row number for loop
Dim lRow As Long 'Last row of data set
Dim ms As Worksheet
Dim mVar1() As Variant
Dim mVar2() As Variant
Dim mVar3() As Variant
Dim rVar() As Variant
Dim num1 As Long
Dim num2 As Long
Set ms = Sheets("Sheet1") 'Change to whatever sheet you need this in
With ms
If .Cells(5, 12).Value = "" Then
MsgBox "Please enter a value in Cell L5 before proceeding."
Else
lRow = .Cells(.Rows.Count, 2).End(xlUp).Row 'This is assuming Column B is populated in full to the bottom of the data set
ReDim rVar(1 To lRow - 8) As Variant
mVar1 = .Range("G9:G" & lRow)
mVar2 = .Range("H9:H" & lRow)
mVar3 = .Range("B9:B" & lRow)
num1 = .Cells(5, 12).Value
num2 = .Cells(5, 13).Value
For i = 1 To UBound(mVar1) 'This is assuming you will be starting the calculation in row 9
If IsNumeric(mVar3(i, 1)) = False And mVar3(i, 1) <> "" Then 'Ensuring Column B is text and not blank
If num1 < WorksheetFunction.Max(mVar1(i, 1), mVar2(i, 1)) And num2 > WorksheetFunction.Min(mVar1(i, 1), mVar2(i, 1)) Then
rVar(i) = 1
Else
rVar(i) = 0
End If
End If
Next i
End If
End With
Range("A9:A" & lRow) = WorksheetFunction.Transpose(rVar)
End Sub

Answer 2

Given that your formula is simple I would expect that the formula approach would calculate faster/better than VBA:
Excel calculates using multiple cores: VBA only uses 1
The overhead of transferring data to VBA and back to Excel is
substantial
Excel can calculate over a million simple formulas per second
Excel can automatically recalculate efficiently if any of the data
changes, but you would have to rerun the entire VBA sub.
I would recommend seeing how long the formula approach takes in practice: I would be surprised if it calculates in more than a second.