VBA - Change Calculation Settings Of Workbook To Speed Up Macro

I have a range of cells ( C2, C5, C8:N1007, P8:P1007 ....) on a worksheet that I want to be able to clear the contents of through a macro - worksheet is entitled Database

I have 3 additional worksheets all of which have summary information on and some of the formulas are huge.

I've inserted a module and produced this code;

Sub ClearContents()
Application.Calculation = xlCalculationManual
Range("C2, C5, C8:N1007, P8:P1007, ....").ClearContents
Application.Calculation = xlCalculationAutomatic
End Sub

Because of all the 3 summary page formulas the code is taking a few seconds to run.

I'm new to VBA and just wondered whether I could switch the calculation setting for the entire workbook onto manual at the beginning of the code and then switch it back to automatic at the end of the code? Think this might speed things up.