Access to Excel: Decrease Runtime of Excel VBA - excel

Question

Similar versions of this question probably have been asked before, but I had questions regarding this issue.
Basically for my function, I just want to run simple a spell check on selected tables from Microsoft Access. Since Access doesn't support individual highlighting all too well in reports, I have the data exported to an Excel file and have VBA run tests for any errors there. After searching online for tips, I have the current code to run faster than what I originally had. But ideally no matter the size of the table I want the function to run under 10 minutes. But currently for some of them, for tables that have 500k+ cells the runtime can still go past 30 minutes. So I was wondering if anything further can be done to better enhance the runtime of this.
Private Function Excel_Parser(outFile As String, errorCount As Integer, ByVal tName As String)
' EXCEL SETUP VARIABLES
Dim OpenApp As Excel.Application
Set OpenApp = CreateObject("Excel.Application")
Dim parserBook As Excel.Workbook
Dim parserSheet As Excel.Worksheet
' Opening exported file
Set parserBook = OpenApp.Workbooks.Open(outFile, , , , , , , , , , , , , , XlCorruptLoad.xlRepairFile)
If parserBook Is Nothing Then
status2 = "Failed to set Workbook"
Exit Function
Else
status3 = "Searching [" & tName & "] for errors"
Set parserSheet = parserBook.Worksheets(1)
' --------------------------------------------------------------------------------
' Fetch Table information
lastCellAddress = parserSheet.Range("A1").SpecialCells(xlCellTypeLastCell).Address
Dim rng As Range
Set rng = parserSheet.Range("A1:" & lastCellAddress)
' --------------------------------------------------------------------------------
' Populating entire table data from Excel into array to save runtime.
Dim dataArr() As Variant, R As Long, C As Long
dataArr = rng.Value2
' Parsing through table data array
nRows = UBound(dataArr, 1)
nCols = UBound(dataArr, 2)
fileOuterLoop1 = Time
For R = 1 To nRows
For C = 1 To nCols
cCell = CStr(dataArr(R, C))
status4 = "Now running check on cell: [" & cCell & "]"
If cCell <> "" Or Not (IsNull(cCell)) Then
If Not OpenApp.Application.CheckSpelling(cCell) Then
errorCount = errorCount + 1
' Change cell status
vArr = Split(parserSheet.Cells(1, C).Address(True, False), "$")
fCol = vArr(0)
xDef = fCol & R
parserSheet.Range(xDef).Interior.Color = RGB(255, 213, 124)
End If
End If 'End of cCell is null check
Next C
Next R
fileOuterLoop2 = Time
fCheck = Format(fileOuterLoop2 - fileOuterLoop1, "hh:mm:ss")
' --------------------------------------------------------------------------------
parserSheet.Columns.AutoFit
status7 = "Loop Finished. Runtime: " & fCheck
' Save and Cleanup
OpenApp.DisplayAlerts = False
parserBook.SaveAs FileName:=outFile, FileFormat:=xlWorkbookDefault, ConflictResolution:=xlLocalSessionChanges
parserBook.Saved = True
parserBook.Close SaveChanges:=False
OpenApp.DisplayAlerts = True
Set parserSheet = Nothing
Set parserBook = Nothing
Set OpenApp = Nothing
' Return errorCount for database
Excel_Parser = errorCount
End If
End Function
outFile is a PATH string, where file exists from a TransferSpreadsheet command. And "status" variables are just error log textboxes in the Access form. I have tried adding in both Access' and Excel's versions of ScreenUpdating or Echo but I found that these commands actually make my function runtime slightly slower.

Answer 1

Two things:
Do you use status4 somewhere in your code to show current state of work and just omitted it here in the sample? If so, think about not displaying it for every loop, but maybe only every 50 steps by using Mod operator.
See https://learn.microsoft.com/en-us/office/vba/language/reference/user-interface-help/mod-operator
You should avoid screen refreshs and more on every loop in Excel by setting this before the loop:
OpenApp.ScreenUpdating = False
OpenApp.EnableEvents = False
OpenApp.Calculation = Excel_XlCalculation.xlCalculationManual
And this after the loop:
OpenApp.ScreenUpdating = True
OpenApp.EnableEvents = True
OpenApp.Calculation = Excel_XlCalculation.xlCalculationAutomatic
It can end in a massive speed up. Give it a try.