Improved scaling of an ordered event stream (OES) is disclosed. In contrast to conventional scaling of an OES that, in immediate response to loading exceeding a given processor performance level, merely divides a segment into segments having similar key space size, and then determines an alternate OES topology. The alternate OES topology can be selected from among ranked alternate OES topologies. The alternate OES topology can be implemented where the expected performance will meet a threshold level of improvement over an existing OES topology. Moreover, the alternate OES topology of the disclosed subject matter can comprise two or more two new segments that can have dissimilar key space sizes. Additionally, the two or more two new segments of the alternate OES topology can provide the same, or similar, loading relative to performance levels of corresponding processing instances, even where the performance levels of corresponding processing instances are also dissimilar.