Refresh control

I have a pdf where the user enters info and the last page does all the calculation.  The calculation is done in the fields, it involves averages.  It is slow because each time any information is entered all the fields on the last page recalulates.  I would like to switch off recalculation on that page until the user clicks a "calculate" button.  Is that possible?

Or even if I could switch off refresh for the entire document until a button is clicked.

I found this code but I am not sure where to put it or how to make it work.  Can anyone help?

Thanks in advance

{

        this.delay = true;

}

{

        this.delay = false;

}