As the number of programs concurrently executing increases, the amount of CPU processing time available for each program eventually decreases. This, in turn decreased the execution speed for each program.

• 随着同时执行程序的数目不断增加，每个程序占有cpu有效的处理时段的长短；最终就会减少.；这反过来就会降低每个程序的执行速度