1. A system comprising: at least one processor; a memory connected to the at least one processor; and at least one program module comprising a profile guided optimizing compiler that: receives profiling data associated with a first version of a program; identifies portions of the profiling data associated with the first version of the program affected by changes made to the first version of the program that are included in a second version of the program; and uses portions of the profiling data associated with the first version of the program not affected by changes made to the first version of the program that are included in the second version of the program, to generate an optimized executable for the second version of the program.