1. A method for controlling utilization of a rapid access memory in a computer system having both a slow access memory and a rapid access memory, said slow access memory storing a plurality of computer programs having instructions for controlling said computer system; comprising the steps of: determining for each program the number of instructions contained in the respective program that require access to memory during execution; dividing the number of program instructions that require access to memory during execution by a value indicating the total amount of memory space required by the respective program to determine a quotient for each program; comparing the quotients for each program with one another; transferring the program with the highest quotient from the slow access memory to the rapid access memory; and successively filling any remaining space in the rapid access memory with the programs having the next highest quotients.