Parallel program has significant percentage of memory requests that target only private data, which does not need to resolve cache coherence conflicts. Yet traditional coherence protocol does not distinguish between shared and private blocks, which leaves much optimization space. An optimized cache coherence protocol, called PMESI, which dynamically deactivates coherence maintenance for private memory space, was suggested. PMESI achieves two distinguishing features: the reduction of memory access latency and system power consumption. Simulation results on the cycle accurate simulator show that 54% memory references can be efficiently optimized and the program execution time is reduced 9% on average.