With "Automatic" or "Automatic Except for Data tables" options: When I change anything, even a cell with no dependable formulas, Excel recalculates everything.
With "Manual": no problem of course.
Just to make sure, even when I open a new sheet and type "A" in a random cell, Excel recalculates the workbook. It freezes a bit and I see "Calculating: (8 processors) xx%" message.
I am forced to work on manual now, but it's not really comfortable.
Remark: I don't know if this is useful but : there is one VBA code I use on one of the sheets, which is activated manually (a button activating the code)