Excel VBA: Writing an array to cells is very slow

Question

I am working with VBA in Excel to retrieve some information from the Reuters 3000 Database. The data I retrieve comes as a bidimensional array consisting of one column hold

Answer 1

By not selecting the sheet, you can add a bit more speed. Instead of

Sheets("Data").Activate
Date_Arr = Range(Cells(3, 106), Cells(3, 106).End(xlDown))
loadDateArray = Date_Arr

Try

With Sheets("Data")
Date_Arr = .Range(Cells(3, 106), Cells(3, 106).End(xlDown))
End With

Answer 2

This is what I did to improve the performance:

• Avoid selecting the cell when the value is going to be written. This was a suggestion of Tim Williams.
• I set the property Application.Calculation to xlCalculationManual

• Instead of using the Find() function to search for the date, I loaded all the dates from the worksheet into an array and iterate over this array to get the row number. This turns out to be faster than the Find() function.

  Private Function loadDateArray() As Variant
  
      Dim Date_Arr() As Variant
  
      Sheets("Data").Activate
      Date_Arr = Range(Cells(3, 106), Cells(3, 106).End(xlDown))
      loadDateArray = Date_Arr
  
  End Function
  
  Private Function getDateRow(dateArray As Variant, dateToLook As Variant)
  
      Dim i As Double: Dim dateRow As Double
  
      For i = LBound(dateArray, 1) To UBound(dateArray, 1)
          If dateArray(i, 1) = dateToLook Then
              dateRow = i
              Exit For
          End If
      Next i
  
      getDateRow = dateRow
  
  End Function
  

Thank you all for your help!