Query-Style Custom Function needs speed boost!

I have created a custom function (GetData) that I use to pull data from a "database" (which I update in the Fin_Data tab). It works well, however the report I need requires that I use requires that I call this function in 10,000+ cells, and as a result the report takes over 4 hours to recalculate. I would really appreciate any help/advice/code-tweaks/changes that could be offered to cut down on this run-time, thanks in advance!



I've included the function below and attached a sample spreadsheet with report to facilitate/encourage tinkering. The data source is normally ~11,000 rows and the report itself is 1,000 rows and has an additional 50 columns but has been reduced to accommodate the file size limitations to upload.

Function GetData(IInum As String, Scenario As String, Version As String, FinCat As String, _
    FinType As String, Yr As String, Func As String, Acct As String, Region As String, OngComp As String, _
    RunInc As String, Vw As String, Mnth As String) As Double
' This is some help on this function!

    Application.Volatile (True)

    Dim FinalDataRow As Double, DataColumn As Double
    Dim IIidCol As Double, ScenarioCol As Double, VersionCol As Double, FinTypeACol As Double
    Dim FinTypeBCol As Double, YearCol As Double, FunctionCol As Double, AcctCol As Double
    Dim RegionCol As Double, OngCompCol As Double, RunIncCol As Double
    Dim PLViewCol As Double, CashViewCol As Double, CapViewCol As Double, BusUnitCol As Double
    Dim i As Integer, MnthNum As Integer
    
    With ThisWorkbook.Worksheets("Fin_Data")
        'Define Columns
        IIidCol = .Range("1:1").Find(What:="ITM_ID", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        ScenarioCol = .Range("1:1").Find(What:="SCENARIO_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        VersionCol = .Range("1:1").Find(What:="VERSION_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        FinCatCol = .Range("1:1").Find(What:="FIN_CAT_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        FinTypeCol = .Range("1:1").Find(What:="FIN_TYPE_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        YearCol = .Range("1:1").Find(What:="YR_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        FunctionCol = .Range("1:1").Find(What:="FXNL_AREA_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        AcctCol = .Range("1:1").Find(What:="ACCT_TYPE_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        RegionCol = .Range("1:1").Find(What:="RGN_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        OngCompCol = .Range("1:1").Find(What:="CPLT_ONG_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        RunIncCol = .Range("1:1").Find(What:="FIN_SUB_TYPE_NM", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        PLViewCol = .Range("1:1").Find(What:="PL_VW", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        CashViewCol = .Range("1:1").Find(What:="CASH_VW", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        CapViewCol = .Range("1:1").Find(What:="CAP_VW", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        BusUnitCol = .Range("1:1").Find(What:="Bus Unit", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        
        If Mnth = "Q1" Then
            DataColumn = .Range("1:1").Find(What:="Q1 Total", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        ElseIf Mnth = "Q2" Then
            DataColumn = .Range("1:1").Find(What:="Q2 Total", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        ElseIf Mnth = "Q3" Then
            DataColumn = .Range("1:1").Find(What:="Q3 Total", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        ElseIf Mnth = "Q4" Then
            DataColumn = .Range("1:1").Find(What:="Q4 Total", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        ElseIf Mnth > 0 And Mnth < 13 Then
            MnthNum = CInt(Mnth)
            DataColumn = MnthNum - 1 + .Range("1:1").Find(What:="JAN", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        Else 'Month # is invalid, give FY number
            DataColumn = .Range("1:1").Find(What:="FY Total", LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, MatchByte:=False).Column
        End If
        FinalDataRow = .Cells(Application.Rows.Count, 1).End(xlUp).Row
        GetData = 0
        
        For i = 2 To FinalDataRow
            If .Cells(i, IIidCol).Value = IInum Or IInum = "ALL" Or .Cells(i, BusUnitCol).Value = IInum Then  'Check II Number
                If .Cells(i, ScenarioCol).Value = Scenario Or Scenario = "ALL" Then  'Check Scenario
                    If .Cells(i, VersionCol).Value = Version Or Version = "ALL" Then  'Check Version
                        If .Cells(i, FinCatCol).Value = FinCat Or FinCat = "ALL" Then  'Check Financial Category (Dir, Indr, Res)
                            If .Cells(i, FinTypeCol).Value = FinType Or FinType = "ALL" Then  'Check Fin Type (Revenue, Save, Spend)
                                If .Cells(i, YearCol).Value = Yr Or Yr = "ALL" Then  'Check Year
                                    If .Cells(i, FunctionCol).Value = Func Or Func = "ALL" Then  'Check Functional Area
                                        If .Cells(i, AcctCol).Value = Acct Or Acct = "ALL" Then  'Check Account
                                            If .Cells(i, RegionCol).Value = Region Or Region = "ALL" Then  'Check Region
                                                If .Cells(i, OngCompCol).Value = OngComp Or OngComp = "ALL" Then  'Check Ongoing/Completion
                                                    If .Cells(i, RunIncCol).Value = RunInc Or RunInc = "ALL" Then  'Check Run-Rate/Incremental
                                                        If (Vw = "PL" And .Cells(i, PLViewCol).Value = 1) Or (Vw = "Cash" And .Cells(i, CashViewCol).Value = 1) Or (Vw = "Cap" And .Cells(i, CapViewCol).Value = 1) Then  'Check View to be shown
                                                            If (Vw = "Cap" And .Cells(i, AcctCol).Value Like "*Credit*") Then
                                                                GetData = GetData - .Cells(i, DataColumn).Value
                                                            Else
                                                                GetData = GetData + .Cells(i, DataColumn).Value
                                                            End If
                                                        End If
                                                    End If
                                                End If
                                            End If
                                        End If
                                    End If
                                End If
                            End If
                        End If
                    End If
                End If
            End If
        Next i
    End With
    
End Function

Your method is too complicated to check through in detail. I am very simple minded, you see

Looking at your final worksheet, it is very similar in layout to many of the reports I had to produce. I usually used pivot tables (sometimes more than one) with VLOOKUP() to transfer data to the final sheet.

This often needed extra calculated columns in the data to analyse the data to fit a PT.

Not knowing your organisation setup etc. ........... I usually handled monthly reporting - doing the calculations once and distributing just the final reports.

Your boss does not need to see a pivot table.
As stated, it is just used as a link to the properly formatted report.