As mass customization becomes more pervasive in many sectors, researchers need to update traditional approaches to the optimization of critical performance and design parameters in order to help companies in their effort to implement this strategy. In general, implementation of mass customization from a manufacturing perspective is frequently focused on shortening cycle times, reducing production cost, and increasing throughput rate of parts. In this paper, process structure modularity impact on manufacturing lead times and throughput rates is explored. An important precondition to explore these relationships is the awareness that process modularity is conceptualized and quantified in an appropriate way. For this purpose, three independent modularity measures were employed to provide more reliable assessment of this system property. The relationships were investigated on the basis of simulation experiments using deterministic models of alternative process structures. For the purpose of the relationships exploration, two case studies were conducted, theoretical and practical ones. The results from the experiments showed that there are moderate correlations between process modularity and manufacturing lead time (ρ = −0.45), as well as between process modularity and throughput rate (ρ = 0.45).