Need help to optimize appending tables created from config table in Power Query

Hi Bamse 

Oh yes, the new code editor are truly terrible.

Not sure if your idea will actually improve performance, but the code for it would be this:

let
GetConfig = () =>
let
Config = #table({"Param1", "Param2", "Param99"},
{
{ "Value A1", "Value A2", "Value A99" },
{ "Value B1", "Value B2", "Value B99" }
})
in
Config,

GetTable = (Param1, Param2, Param99) =>
let
ResultTable = #table({"Column"},
{
{ "Demo " & Param1 & ", " & Param2 & ", " & Param99 }
})
// Here some heavy lifting (merge, group e.c.t. is done and data is read from different sources)
// I want to keep this isolated to the 'small' tables instead of doing this all at once on a massive table.
in
ResultTable,
    Custom1 = Table.ToRecords(GetConfig()),
    Custom2 = List.Transform( Custom1, each GetTable([Param1], [Param2], [Param99]) ),
    Custom3 = Table.Combine(Custom2)
in
    Custom3

But I would try the following: Reduce the number of function parameters by putting them all together into one record like so:

let
GetConfig = () =>
let
Config = #table({"Param1", "Param2", "Param99"},
{
{ "Value A1", "Value A2", "Value A99" },
{ "Value B1", "Value B2", "Value B99" }
})
in
Config,

GetTable = (MyParameterRecord) =>
let
ResultTable = #table({"Column"},
{
{ "Demo " & MyParameterRecord[Param1] & ", " & MyParameterRecord[Param2] & ", " & MyParameterRecord[Param99] }
})
// Here some heavy lifting (merge, group e.c.t. is done and data is read from different sources)
// I want to keep this isolated to the 'small' tables instead of doing this all at once on a massive table.
in
ResultTable,
    Custom1 = Table.ToRecords(GetConfig()),
    Custom2 = List.Transform( Custom1, each GetTable(_) ),
    Custom3 = Table.Combine(Custom2)
in
    Custom3