A method for automatic identification of execution phases in load test data includes receiving load test data indicating processor utilization for threads over a period of time divided into a plurality of intervals. For each pair of proximate intervals, it is determined whether thread-wise processor utilization for a first interval is statistically indistinguishable from that of a second interval. The pair of proximate intervals is combined when it is determined that the processor utilization for the first interval is statistically indistinguishable from that of the second interval. Each of the pair of proximate intervals is divided into subintervals when it is determined that the first interval is not statistically indistinguishable the second interval. One or more execution phases are automatically identified as occurring between proximate intervals that are not substantially equivalent.