The use of agile methods in the execution of large-scale software development is increasing. To find out more about the effect of this on project performance, information was collected about 196 Norwegian IT-projects. Increased project size was associated with decreased project performance for both agile and non-agile projects, but the projects using agile methods had better performance than the non-agile projects for all examined project size categories. Flexible scope, frequent deliveries to production, a high degree of requirement changes and more competent providers are candidates to explain the better performance of agile projects.