Very slow Power Query refresh

JCouture17 

Context differs so don't draw conclusions from what's below. It's just to give you a sense of some refresh times

PC Specs: Core i7 / SSD / 8Gb / Win11 / MSFT 365-64Bits

Created following 2 Tables in an Excel workbook, each 1 Million rows. Required columns only. All [Serial #] match:

Query1 - Merge tables + Expand

let
    Source = Table.NestedJoin(
        SharePoint, {"Serial #"},
        CAPScrapWeekly, {"Serial #"},
        "CAPScrapWeekly", JoinKind.LeftOuter
    ),
    Expanded = Table.ExpandTableColumn(Source, "CAPScrapWeekly",
        {"CQ", "Prod Date"}, {"CQ", "CAPScrapWeekly.Prod Date"}
    )
in
    Expanded

Query2 - Same as above + your extra steps

let
    Source = Table.NestedJoin(
        SharePoint, {"Serial #"},
        CAPScrapWeekly, {"Serial #"},
        "CAPScrapWeekly", JoinKind.LeftOuter
    ),
    Expanded = Table.ExpandTableColumn(Source, "CAPScrapWeekly",
        {"CQ", "Prod Date"}, {"CQ", "CAPScrapWeekly.Prod Date"}
    ),
    AddedProdDate = Table.AddColumn(Expanded, "Prod Date", each
        if DateTime.Time([Datetime]) < Time.From("07:00")
        then DateTime.Date(Date.AddDays([Datetime],-1))
        else DateTime.Date([Datetime]),
        type date
    ),
    AddedWeekNum = Table.AddColumn(AddedProdDate, "WeekNum", each
        Text.PadStart(Text.From(Date.WeekOfYear([Prod Date])),2,"0"),
        type text
    ),
    ReplacedNullCQ = Table.ReplaceValue(AddedWeekNum,null,"-",Replacer.ReplaceValue,{"CQ"}),
    ReplacedProdDate = Table.ReplaceValue(ReplacedNullCQ,
        each [CAPScrapWeekly.Prod Date],
        each [CQ],
        (a,b,c) as date => if c <> "-" then b else a,
        {"Prod Date"}
    ),
    RemovedCapsProdDate = Table.RemoveColumns(ReplacedProdDate,{"CAPScrapWeekly.Prod Date"}),
    AddedMonth = Table.AddColumn(RemovedCapsProdDate, "Month", each Date.MonthName([Prod Date]), type text),
    AddedDateShift = Table.AddColumn(AddedMonth, "Date-Shift", each
        if DateTime.Time([Datetime])>=Time.From("7:00") and DateTime.Time([Datetime])<Time.From("19:00")
        then Date.ToText([Prod Date],"yyyy-MM-dd") & "-" & "D"
        else Date.ToText([Prod Date],"yyyy-MM-dd") & "-" & "N",
        type text
    )
in
    AddedDateShift

Hope this helps a bit