1. A method, in a data processing system, for automatically identifying performance regression between builds of a computer program based on trace data obtained from a plurality of executions of a first and second build of a computer program, comprising: obtaining a plurality of call tree data structures corresponding to the trace data for the plurality of executions of the first and second builds of the computer program; generating a minimized call tree data structure from the plurality of call tree data structures for each of the first and second builds of the computer program, wherein the minimized call tree data-structure includes a minimum set of nodes that are consistent between the plurality of call tree data structures; subtracting the minimized call tree data structure for the second build of the computer program from the minimized call tree data structure of the second computer program to thereby generate a subtracted minimized call tree data structure; and outputting the subtracted minimized call tree data structure.