Abstract: An arrangement for measuring the load handling capacity of a stored program control process control system. The process control system is first operated in a monitor mode without any load in order to identify the instructions which must be executed independently of load and therefore, may be characterized as "overhead work" instructions. While operating in the no load or monitor mode, each instruction which is executed is flagged by placing "1" in a flag position of the instruction word. The machine includes provisions for executing instructions so flagged with standard machine timing and for executing unflagged instructions with extended machine timing. The unflagged instructions are termed "load related work" instructions and by extending the time required to execute such instructions, the apparent load to the machine is increased, increasing the machine's apparent occupancy. The time for executing a "load related work" instruction is extended by integral numbers of clock frames.