Traditionally, only basic signal timings have been optimized in order to minimize delays and stops of private vehicles. Transit Signal Priority parameters and subsequent beneficiaries, such as transit vehicles and passengers, are usually neglected in the signal timing optimization process. Little research has been done to reveal specific benefits of optimizing Transit Signal Priorities and whether consideration should be given to both private vehicles and others when optimizing signal timings. Research presented here tests optimization of three performance measures (auto delay, transit delay, and person delay) by adjusting signal timings in different ways. A Genetic Algorithm formulation, coupled with a high-fidelity microsimulation model, is used to investigate benefits of each optimization on a large urban traffic corridor. The results show that basic signal timings are the most important measure to optimize when transit and private cars share a corridor. Also, the findings show that personal delay represents a suitable objective function for optimization of signal timings.