Automatic recalculation supports two methods of recalculations: Foreground and As Needed.
When Foreground is set, NExS enforces minimal recalculation, which means that only the cells in the spreadsheet which are potentially affected by an operation which you perform (such as editing a cell, or moving a range of cell) are recalculated. This feature minimizes the work performed during recalculation and thus speeds up your computations. Minimal recalculation is in effect whenever the recalculation mode in the Recalc Options dialog is set to Automatic and the method is set to Foreground.
When As Needed is set NExS enforces frugal recalculation, which further reduces the number of cell that need to be computed. The performance gain in recalculation can be significant, depending on the size and complexity of the sheet. Frugal recalculation is in effect whenever the recalculation mode in the Recalc Options dialog is set to Automatic and method is set to As Needed.