We attack the problem of user fatigue in using an interactive genetic algorithm to evolve user interfaces in the XUL interface definition language. The genetic algorithm combines a set of computable user interface design metrics with subjective user input to guide the evolution of interfaces. User interface specifications are encoded as individuals in a genetic algorithm’s population and their fitness is computed from a weighted combination of user interface design guidelines and user input. We show that we can reduce human fatigue in interactive genetic algorithms (the number of choices needing to be made by the designer), by 1) only asking the user to pick two user interfaces from among ten shown on the display and 2) by asking the user to make the choice once every t generations. Our goal is to provide user interface designers with a tool that can be used to explore innovation and creativity in the design space of user interfaces and make it easier for end-users to further customize their user interface without programming knowledge.