I'm astonished at the magnitude of the difference correct prediction can make in a scenario where the effect of a misprediction is to either increment a sum or

I'm astonished at the magnitude of the difference correct prediction can make in a scenario where the effect of a misprediction is to either increment a sum or not. How is that possible? How many clock cycles does an accurate prediction save in this context, and how many are used in moving through the loop and evaluating the condition?