Relocation introduces overhead into the computer. Overhead can be defined as the increment in resources (time in this case) that is required by a more complex system to do essentially the same task on a simpler system. For example, in the CSC-1, all addresses that the program generates are real already -- nothing has to be added to them. Of course the CSC-1 cannot run more than one program at a time. Running the same user program on the CSC-1 and on a machine with run-time relocation shows the CSC-1 to be faster. Suppose that the program on the CSC-1 completes in 8 seconds, and the same program on the other machine completes in 10 seconds. Then we would say that there was a 25% slowdown of the program on the new machine, calculated by taking (10-8)/8 = 2/8 = .25 = 25%

We could also say that there is a 25% overhead on the new machine due to the memory relocation mechanism. To calculate overhead, run the same program on both machines and find the difference. This difference, which is the extra time required by the new hardware, is the overhead, or time "wasted" by the new mechanism. In order to make comparisons, we standardize these differences by dividing them by the slower running time to come up with a percentage.