Performance degradation due to routing overhead is a serious impediment to fulfilling quality of service (QoS) in mobile ad hoc networks (MANETs). Therefore, analyzing the impact of routing overhead in a real-time environment becomes critical to developing efficient routing protocols and provisioning network performance. We develop a statistical-analytic approach to studying the impact of the routing overhead on delay and throughput in a real-time MANET testbed. The approach helps us in deriving statistical models of delay and throughput which, in turn, enables us to analyze the behavior of routing protocols beyond the scenarios configured in the testbed. In addition, we conduct a simple analysis of measuring network bandwidth consumed by routing overhead in various environments. Although optimized link state routing (OLSR) and ad-hoc on-demand distance vector (AODV) routing protocols are investigated as case studies in this paper, our approach and findings are applicable to other routing protocols as well.