Performance Theory is a rich topic, touching on many academic fields of study. This guide focuses primarily on the literary, theatrical and philosophical. Librarians in those areas are more than happy to help you think through a project or find what you need.
The subject headings to search in the library catalog (or WorldCat) are performance art, performing arts philosophy or theater philosophy. There's also literature philosophy and motion pictures philosophy, to round out the picture. If you run into difficulties finding what you need, ask!