A survey program with multiple science goals will be driven by multiple technical requirements. On a ground-based telescope, the variability of conditions introduces yet greater complexity. For a program that must be largely autonomous with minimal dwell time for efficiency it may be quite difficult to foresee the achievable performance. Furthermore, scheduling will likely involve self-referential constraints and appropriate optimization tools may not be available. The LSST project faces these issues, and has designed and implemented an approach to performance analysis in its Operations Simulator and associated post-processing packages. The Simulator has allowed the project to present detailed performance predictions with a strong basis from the engineering design and measured site conditions. At present, the Simulator is in regular use for engineering studies and science evaluation, and planning is underway for evolution to an operations scheduling tool. We will describe the LSST experience, emphasizing the objectives, the accomplishments and the lessons learned.