Fetching text property by time

Whilst the code you posted is a bit inefficient, I can't see a reason this loop would take 10 minutes unless you're running the insert query on every iteraton of the loop.   Here are some ways you might optimize this, including construction of a single query for all inserts that would run at the end of the loop as a batch insert using a DataTable object.  Also, added a convenience TimePeriod struct object for better readability and corrected the TimeDimHelper call & strDate part mentioned above.  Hopefully this can help you.

Dim strStartPeriod As String = "2025M1"
Dim strEndPeriod As String = "2026M12"

Dim mbrId As Integer = 12345
Dim Mbr As String = "SalesGrowth"
Dim desc As String = "Sales Growth Trend (YoY)"

' Call the subroutine to build and run the SQL
RunInsert(si, mbrId, Mbr, desc, strStartPeriod, strEndPeriod)

Public Sub RunInsert(si As SessionInfo, mbrId As Integer, Mbr As String, desc As String, strStartPeriod As String, strEndPeriod As String)
	Dim startPeriod As New TimePeriod(strStartPeriod, si)
	Dim endPeriod As New TimePeriod(strEndPeriod, si)

	Dim timeIdCache As New Dictionary(Of String, Integer)
	Dim dt As New DataTable("MemberTextbyDate_Table")

	' Define columns expected by the destination table
	dt.Columns.Add("MemberId", GetType(Integer))
	dt.Columns.Add("MemberName", GetType(String))
	dt.Columns.Add("MemberDescription", GetType(String))
	dt.Columns.Add("Text", GetType(String))
	dt.Columns.Add("Date", GetType(String))

	For year As Integer = startPeriod.Year To endPeriod.Year
		Dim maxMonth As Integer = If(year = endPeriod.Year, endPeriod.Month, 12)
		Dim minMonth As Integer = If(year = startPeriod.Year, startPeriod.Month, 1)

		For month As Integer = minMonth To maxMonth
			Dim strDate As String = $"{year}M{month}"

			Dim timeID As Integer
			If Not timeIdCache.TryGetValue(strDate, timeID) Then
				timeID = TimeDimHelper.GetIdFromName(strDate)
				timeIdCache(strDate) = timeID
			End If

			Dim myVaryByTimeId As Integer = BRApi.Finance.Members.GetMemberId(si, DimType.Time.Id, strDate)
			Dim mbrText As String = BRApi.Finance.UD.Text(si, 9, mbrId, 2, -1, myVaryByTimeId)

			If Not String.IsNullOrWhiteSpace(mbrText) Then
				dt.Rows.Add(mbrId, Mbr, desc, mbrText, strDate)
			End If
		Next
	Next

	If dt.Rows.Count > 0 Then
		Dim dbLocation As String = "App:MemberTextbyDate_Table" ' or wherever your table is defined
		Dim useBulkInsert As Boolean = True

		Using dbConnApp As DbConnInfo = BRApi.Database.CreateApplicationDbConnInfo(si)
			BRApi.Database.SaveCustomDataTable(si, dbLocation, dbConnApp, dt, useBulkInsert)
		End Using
	End If
End Sub

' -------------------------------
'         TimePeriod struct
' -------------------------------
Public Structure TimePeriod
    Public Property Year As Integer
    Public Property Month As Integer
    Public Property Id As Integer

    Public Sub New(name As String, si As SessionInfo)
        If Not Regex.IsMatch(name, "^\d{4}M\d{1,2}$") Then
            Throw New ArgumentException("Invalid period format. Expected 'YYYYM#'.", NameOf(name))
        End If

        Year = Integer.Parse(name.Substring(0, 4))
        Month = Integer.Parse(name.Substring(5))
        Id = BRApi.Finance.Time.GetIdFromName(si, name)
    End Sub
End Structure