In this paper we evaluate the performance of a large-scale POWER8 symmetric multiprocessor (SMP) system with eight processors. We focus our attention on cache and memory subsystems, analyzing the characteristics that have a direct impact on high-performance computing and analytics applications. We provide insight into the relevant characteristics of the POWER8 processor using a set of microbenchmarks. We also analyze the POWER8 SMP at the system level using the well-known roofline model. Using the knowledge gained from these micro-benchmarks, we optimize three applications and use them to assess the capabilities of the POWER8 system. The results show that the POWER8 - based SMP system is capable of delivering high performance for a wide range of applications and kernels.