Systems and Networks on Chips (NoCs) are a prime design focus of many hardware manufacturers. In addition to functional verification, which is a difficult necessity, the chip designers are facing extremely demanding performance prediction challenges, such as the need to estimate the latency of memory accesses over the NoC. This paper attacks this problem in the setting of designing globally asynchronous, locally synchronous systems (GALS). We describe foundations and applications of a combination of compositional modeling, model checking, and Markov process theory, to arrive at a viable approach to compute performance quantities directly on industrial, functionally verified GALS models.