1. In a computer system for executing a program comprising a plurality of methods compiled into bytecode for interpretation at runtime by a runtime interpreter, a method for improving runtime execution of said program comprising: creating a compiled code slot in memory which is associated with a particular method, said compiled code slot for storing a pointer to a memory address; initializing the compiled code slot to store a pointer to a handler, said handler for invoking compilation of said particular method; upon first invocation of the particular method, invoking said handler for performing substeps comprising: (i) compiling said particular method into a compiled method comprising native machine code for a target microprocessor, including mapping bytecode for a method being called into native machine code for execution by a target microprocessor, (ii) storing in the compiled code slot a pointer to said compiled method, including generating a machine code call instruction for transferring execution of the program to said compiled method that is located at a memory address pointed to by the pointer stored in said compiled code slot, so that the particular method can be accessed by a method which is itself compiled into native machine code for the target microprocessor, and (iii) executing said particular method by executing the compiled method comprising native machine code for the target microprocessor; and upon subsequent invocation of the particular method by a method which is itself compiled into native machine code for the target microprocessor, executing said particular method by executing the compiled method which is pointed to by the pointer stored in the compiled code slot for said particular method.