Yes, some components of QuarkXPress are multi-threaded and can make use of multiple-core computers. The overall layout process runs on a single thread, including all rendering, calculation (for example, the text engine when it calculates text flow), and shapes manipulation. However, there are specific areas of the application where this is done, the clearest example is QuarkVista (Picture Effects). Other processes that use multi-threading are the reading of QuarkXPress project files, and some aspects of the way in which external files are monitored for Composition Zones and Job Jackets in QuarkXPress.