The accumulated change in values representative of actions taken by a processor, such as the number of email messages processed by an email server, in a given time period is determined. Actions are represented as data points on a plot. Look-ahead intervals are defined for each point. Candidate pairs of points are determined for each look-ahead interval by comparing the first value in the look-ahead interval with other values in the look-ahead interval. A candidate pair comprises the first point and another point having a lesser value. If a candidate pair has a value therebetween, the candidate pair is discarded. If, however, a candidate pair has no value therebetween, the first value of the candidate pair is a peak value for the look-ahead interval. The accumulated change is determined by calculating the sum of the peak values, plus the final value, minus the initial value, for the given time period.