You could give this routine a try; it will clear all unlocked cells on all
worksheets in the active workbook (and it should be pretty fast)...
Sub ClearUnlockedCells()
Dim C As Range, FoundCells As Range, SheetName As String
Dim WS As Worksheet, FirstAddress As String
Application.ScreenUpdating = False
Application.FindFormat.Locked = False
SheetName = ActiveSheet.Name
For Each WS In Worksheets
WS.Activate
Set FoundCells = Nothing
With WS.UsedRange
Set C = .Find("", SearchFormat:=True)
If Not C Is Nothing Then
FirstAddress = C.Address
Do
If FoundCells Is Nothing Then
Set FoundCells = C
Else
Set FoundCells = Union(FoundCells, C)
End If
Set C = .Find("", after:=C, SearchFormat:=True)
Loop While Not C Is Nothing And C.Address <> FirstAddress
End If
If Not FoundCells Is Nothing Then FoundCells.Clear
End With
Next
Application.FindFormat.Clear
Worksheets(SheetName).Activate
Application.ScreenUpdating = True
End Sub