Best practice to read tables from Web.Contents source

I made this one to Custom (not in image below but tested in power bi desktop):

The source query is :

let getRemoteRepository = (RepositoryName as text, CostMgmtPath as text, SpecificFolder as text, optional BranchName as text) => 
    let
        RefBranchName = if BranchName <> null then BranchName else null,
        Source = GitHub.Contents(RepositoryName, CostMgmtPath & SpecificFolder, RefBranchName),

        Files = List.Transform(Source, each [
            Name = Record.Field(_, "name"), 
            DownloadUrl = Record.Field(_, "download_url")
        ]),

        CsvFiles = List.Select(Files, each Text.EndsWith(Text.Lower([Name]), ".csv")),

        FilesTable = Table.FromList(CsvFiles, Splitter.SplitByNothing(), {"File Info"}),
        ExpandedTable = Table.ExpandRecordColumn(FilesTable, "File Info", {"Name", "DownloadUrl"}, {"Name", "Location"}),

        AddRelativePathColumn = Table.AddColumn(ExpandedTable, "RecordRelativePath", each 
            let
                a1 = Text.Replace([Location], paramBaseUrlRawGithub, ""),
                a2 = Text.BeforeDelimiter(a1, "?token=", 0),
                t = Text.AfterDelimiter([Location], "?token=", 0)
            in
                [
                    RelativePath = a2,
                    Token = t
                ]
        ),

        ExpandedColumn = Table.ExpandRecordColumn(AddRelativePathColumn, "RecordRelativePath", {"RelativePath", "Token"}),

        AddColumnWithTable = Table.AddColumn(ExpandedColumn, "ResultTable", each 
            let
                a = Csv.Document(
                    Web.Contents(paramBaseUrlRawGithub, [
                        RelativePath = [RelativePath],
                        Query = [token = [Token]]
                    ]),
                    [Delimiter = ",", QuoteStyle = QuoteStyle.Csv]
                ),
                b = Table.PromoteHeaders(a, [PromoteAllScalars=true])
            in
                b
            )   
    in 
        AddColumnWithTable
in getRemoteRepository

I  have 3 different source queries like above one. Poiting to different gitHub folders. 

from this i am filtering tables to get a specific one and creating 20 seperated tables queries. 

let GetCsvContentMart1Table = (tableName as text) =>
    let
        FilteredAllSourceTableUrl = Table.SelectRows(AllTables, each [Name] = tableName)[ResultTable]{0}
    in
        FilteredAllSourceTableUrl
in GetCsvContentMart1Table

Time of loading after disabling parallel uploading is increasing badly... why ?
How to make the best set up when i have 3 different web contents (sharepoint lists, github etc.), after that I am merging them into 1 specific table and filtering to get seperated small csv tables from it? 

What are the experts approaches? 
Best,
Jacek