Forward-Error Correction (FEC) is of key importanceto the robustness of optical communication networks. In particular, Inband-FEC is an attractive option, because it improves channel-performance without requiring an increase of the transmission bandwidth. We have devised and implemented a novel inband FEC method, dubbed FOCUS, for the electronic-mitigation of physical impairments in SDH/SONET optical networks. It is an inherently low-cost approach for both the metro and backbone network regions, scalable to any SDH/SONET rate and capable to significantly increase optical channel performance. This paper analyzes the most sophisticated ones from the plethora of optimizations that were employed to minimize the architectural complexity of FOCUS, falling in: a) Arithmetic operator design, b) Resource sharing and c) Redundant logic elimination. These optimizations were necessary to obtain a prototype, which eventually permitted the first fully successful laboratory evaluation of the FOCUS Inband-FEC method.