The paper investigates the influence of the load factor of the shared memory on the efficiency of multicore systems. Typically, all cores serve threads of one program in parallel by the OpenMP programming technology or execute independent programs. There are no interactions between threads and independent programs, but conflicts can occur when accessing the shared memory. Models of program execution in one core and a multicore computer are developed, considering the probabilities of successful calls and service times of all levels of the shared memory subsystem. The load factor of the first level cache is determined through the ratio of the L1 cache load time to the total execution time of the program. The execution of various types of programs is simulated. A technique for the acceleration coefficient of a multicore computer based on the total load factor of the shared memory has been proposed. Based on this insight, we apply our model to determine the acceleration coefficient for 4-, 8-, 12-and 16core systems for different combinations of system parameters.