1. A method for preserving platform independence of a program while supporting a platform specific implementation of program objects for performance critical program code objects when loading a class during execution of the program, the method comprising the steps of: identifying in a virtual machine a reference to a program object in a platform independent computer program; determining in the virtual machine by a class loader if a platform specific implementation of the same platform independent computer program of said program object has been separately stored in addition to a platform independent implementation of said program object; and, if it is determined in the virtual machine that a platform specific implementation of said program object has been separately stored in addition to a platform independent implementation of said program object, loading said platform specific implementation of said program object in lieu of said platform independent implementation during realtime.