VBA for loop takes too long - vba

Question

Just starting out on VBA, and my code is painfully slow. I have a number of workbooks on a network drive, each with several worksheets. I am trying to fetch data from a number of non-contiguous ranges in each worksheet to a pre-designed worksheet, using the following code:
Private Function GetValue(path, file, sheet, ref)
'retrieve value
'// code
GetValue = ExecuteExcel4Macro(arg)
End Function
Sub UpdateModel1()
sheet = "blah blah"
Application.ScreenUpdating = False
'Outputs
destRow = 31 'destination row
destCol = 6 'destination column
srcRow = 50 'source row
For C = 23 To 31 'loop through source columns
ref = Cells(srcRow, C).Address
Cells(destRow, destCol) = GetValue(path, file, sheet, ref)
destCol = destCol + 1
Next C
Application.ScreenUpdating = True
End Sub
However, using a nested for loop in the sub procedure takes way too long. Any suggestions on how to improve this code? PS: this is an amateur's code, and I am just looking for something that does the work decently.

Answer 1

Here is a working example of what you are trying to do:
Sub TestGetSheetValue()
MsgBox GetSheetValue("N:\Tax Documents\", "Tax Stuff.xlsx", "Sheet1", "R1C3")
End Sub
Function GetSheetValue(strPath As String, strFile As String, strSheet As String, strCellRef As String)
GetSheetValue = ExecuteExcel4Macro("'" & strPath & "[" & strFile & "]" & strSheet & "'!" & strCellRef)
End Function
Obviously change what you pass into the function for your needs, note the address is R1C1 format.
The strSheet is the sheet name, not the sheet index.
Make sure you have a trailing \ on the path
Finally, try not to use names like file, path and sheet for variable names.