You eIther have lots of formulas in the spreadsheet you're working in OR you have another spreadsheet open in the same Excel instance that has a lot of formulas. You need to make sure that you're running your code alone in an instance of excel, whenever possible. Also, before your code begins, you need to add ...
Application.Calculation = xlCalculationManual
and then at the end, you need to add
Application.Calculation = xlCalculationAutomatic
Good luck,
sdwalker