You won't be able to type until the code executes and depending on your processor speed that may take several seconds. I ran

Sub ScratchMacro()
'A basic Word macro coded by Greg Maxey
Dim oCC As ContentControl
Dim I As Long
Dim oRng As Word.Range
For I = 1 To 150
Set oRng = ActiveDocument.Range
oRng.Collapse wdCollapseEnd
oRng.InsertBefore vbCr
ActiveDocument.ContentControls.Add wdContentControlText, oRng
Next
For I = 1 To 400
Set oRng = ActiveDocument.Range
oRng.Collapse wdCollapseEnd
oRng.InsertBefore vbCr
Set oCC = ActiveDocument.ContentControls.Add(wdContentControlDropdownList, oRng)
oCC.DropdownListEntries.Add "Test", "Test'"
oCC.DropdownListEntries.Add "XXX", "XXX"
Next
For I = 1 To 5
Set oRng = ActiveDocument.Range
oRng.Collapse wdCollapseEnd
oRng.InsertBefore vbCr
ActiveDocument.ContentControls.Add wdContentControlDate, oRng
Next
lbl_Exit:
Exit Sub
End Sub

To add the CCs and it takes my PC about 1.5 seconds to process the clear code.