A method is provided for characterizing objects generated during an initial run of a program, each object being characterized by a number of alternative properties which can be chosen. The method includes steps of instrumenting an initial run of program to determine characterization information about each of objects, then determining a desirable property for each object, then determining a correlation between the desirable property and the characterization information for each of the objects. This correlation is then used to select a property for an object that is subsequently created during a run of the program based only upon characterization information about the subsequently created object.