Is the problem that MyCalculation takes some time? Not that it makes any difference here but: perhaps a side-project is to speed that up, like... maybe it is doing a lot of redundant string-to-number conversions: they can chew up way more time than the actual math itself.
Returning to the actual question:
You could have a private global CalculationEnableFlag that you temporarily set to False when the bulk calls occurs (loading up EditTexts with initial values?) and then set back to True and do a single call immediately after.
Or you could do something similar within the calculation Sub to throttle it, ie if if it is less than a second since the last time it was called, then instead set a timer to do the calc in the near future.
Or if that feels too fragile or complex, another way is to have a private global RecalculateFlag that is set whenever one of the source variables changes, and checked regularly by a timer tick that, if the flag is set, clears the flag FIRST and then performs the calculation.