In this talk we will presents the results concerning different aspects of the performance optimization of a swimsuit. The influence of the sewing on the performance has been analyzed: the results have proved a relevant improvements (in term of drag reduction and course time gain) when sewings are not present on the surface of the swimsuit. We will also analyze the stroke: in order to be able to simulate such kind of phenomena the development of a new set of simulation tools able to treat moving domain problems has been developed. A complete reconstruction of the swimmer kinematics is an extremely complex problem. Even the motion of a single arm is hard to be reproduced accurately without considering complex kinematics: in this respect, we have considered and implemented different stroke kinematics with increasing level of complexity.