Copy cells formulas VBA - vba

Question

I did a program in VBA to copy the formulas in each cell in a specific column, I have 30501 points and the program is really slow even to calculate 100 points, there is a better way to do so?
Sub Copyformulas()
Dim i As Integer
Dim cell As Range
Dim referenceRange As Range
Dim a As String
a = "$T$30510"
Set range1= ActiveSheet.Range("A1:A30510")
Set myrange = Range("T16:T30510")
i = 16
Do Until Cells(20, 30510)
With range1
For Each cell In myrange
If cell.HasFormula Then
Cells(i, 35).Value = cell.Address
Cells(i, 36).Value = "'" & CStr(cell.Formula)
i = i + 1
End If
Next
End With
Loop
End Sub

Answer 1

You can use SpecialCells to refine your range. You don't need to use ActiveSheet it is implied.
Set rSource = Range("A16:A30510").SpecialCells(xlCellTypeFormulas)
Sub Copyformulas()
Application.Calculation = xlManual
Application.ScreenUpdating = False
Application.EnableEvents = False
Dim c As Range
Dim rSource As Range
Set rSource = ActiveSheet.Range("A16:A30510").SpecialCells(xlCellTypeFormulas)
For Each c In rSource
c.Offset(0, 34) = c.Address
c.Offset(0, 35) = "'" & c.Formula
Next
Application.Calculation = xlAutomatic
Application.ScreenUpdating = True
Application.EnableEvents = True
End Sub

Answer 2

Try adding the following:
Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False
Application.EnableEvents = False
... Your Code ...
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True
Application.EnableEvents = True
You may only need the first one, but they are all good practice in using. Also, where are you using the With ... End With statement? I don't see any use of it in the block.
It is good practice to use Option Explicit at the top of the module. And range1 and myrange are not declared.
Application.Calculation
When a worksheet is accessed or a range's precedents has changed, Excel will automatically recalculate the formulas on the worksheet. Since you are looping over 30,000 times, this causes Excel to recalculate each time through the loop and, thus, slows down performance.
Application.ScreenUpdating
This line stops Excel from screen flashes and other things that occur as the macro runs.
Application.EnableEvents
This line turns off events, such as Worksheet_Change, so that the event is not triggered. If it is not turned off then any time a change occurs on the worksheet the code in the change event will run. If you have a Worksheet_SelectionChange event then code will run every time you select a different cell. These events are written in the worksheet or workbook objects located in the project window of the VBE and there are many events to choose from. Here is a very simple illustration. Place the following in the Sheet1 object in the project window:
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
MsgBox "Hi!"
End Sub
Now click around on the worksheet. You see it responds to each selection change. Now place the following in a regular module:
Sub TestEnableEvents()
Application.EnableEvents = False
ActiveCell.Offset(1, 0).Select
Application.EnableEvents = True
End Sub
When you run the above code the message box will not be triggered.