velocizzare Function

Buongiorno a tutti, 
Vorrei sapere se c'è il modo di velocizzare il calcolo di questa funzione. 

Ho un foglio con un centinaio di celle contenenti la formula Yahoo per il recupero delle quotazioni di alcuni titoli azionari. Il ricalcolo del foglio ci mette molto tempo. È possibile modificarlo per accorciare i tempi? GRAZIE

Function Yahoo(Symbol As String, SearchParameter As String)

    ' Get near real-time stock quote from Yahoo via JSON query

    Dim URL As String, response As String, stripped As String, inbits() As String, i As Long, Info As String
    Dim request As WinHttp.WinHttpRequest                               ' needs Tools|References|WinHTTP Services
    On Error GoTo Err
    Select Case SearchParameter
     Case Is = "Quote"
     Info = "regularMarketPrice:"
     Case Is = "SName"
     Info = "shortName:"
     Case Is = "LName"
     Info = "longName:"
     Case Is = "Date"
     Info = "regularMarketTime:"
     Case Is = "PClose"
     Info = "regularMarketPreviousClose:"
     Case Is = "Open"
     Info = "regularMarketOpen:"
     Case Is = "DHigh"
     Info = "regularMarketDayHigh:"
         Case Is = "DLow"
     Info = "regularMarketDayLow:"
    Case Else: Info = SearchParameter
    End Select

    URL = "https://query2.finance.yahoo.com/v7/finance/options/" & Trim(Symbol)
    Set request = New WinHttp.WinHttpRequest
    With request
        .Open "GET", URL, True
        .SetRequestHeader "Content-Type", "application/x-www-form-urlencoded; charset=UTF-8"
        .Send
        .WaitForResponse
        response = .responseText
    End With

    If InStr(response, """result"":[]") <> 0 Then GoTo Err1              ' ticker not found
    
    'kludge parse: strip JSON delimiters and quotes
    stripped = Replace(Replace(Replace(Replace(Replace(response, "[", ""), "]", ""), "{", ""), "}", ""), """", "")

    stripped = Replace(stripped, ":", ":,")                             ' keep colons for readability, but make them delimit
    inbits = split(stripped, ",")                                       ' split
    
    i = LBound(inbits)
    Do While inbits(i) <> Info And i <= UBound(inbits) ' find "regularMarketPrice:" tag
        i = i + 1
    Loop
    
   
    If i > UBound(inbits) Then GoTo Err                                 ' not found
    If IsNumeric(inbits(i + 1)) Then Yahoo = Val(inbits(i + 1)) Else: Yahoo = Trim(inbits(i + 1))
    
    
    Exit Function
    
Err:
    
    Yahoo = CVErr(xlErrNA)
Err1:

    Yahoo = "Codice Errato"

End Function