As researchers continue to explore novel technologies for future generations of wireless communications, flexible and adaptable tools are required for testing and development. Software-Defined Radios (SDRs) allow for flexible and reconfigurable signal processing, making them a crucial tool for rapid testing and experimental validation of communication systems. GNURadio is an open source SDR toolkit with functionality to extend it’s core software library by developing Out-Of-Tree (OOT) modules. Our gr-owc OOT module enables SDR capabilities for Optical Wireless Communication (OWC) and serves as a research tool that facilitates real-time experimentation, system-level analysis, and algorithm development in OWC. To effectively support real-time experimentation, the custom signal processing blocks in gr-owc must be computationally efficient to keep up with real-time hardware requirements. This paper presents a study of the Central Processing Unit (CPU) utilization patterns of gr-owc’s signal processing blocks. Namely, we provide insights into the computational efficiency of gr-owc blocks and sample flowgraphs by analyzing CPU utilization with respect to sample rate, hardware deployments, and block configurations. We also introduce recent modifications to these blocks that improve performance while maintaining functionality. Experimental results validate the influence of parameters like compute hardware and coding implementation on CPU usage and reveal the limitations imposed by single-core block processing in GNURadio applications.