To minimize execution time on multiprocessor systems, set ExecuteOnMainThread to False. This setting allows DTS to start multiple threads and process steps in parallel.
However, not all tasks, connections, and applications called by DTS can support multiple threads, including the following:
Connection drivers that are not thread-safe, such as the Microsoft OLE DB Provider for Jet and most file-based data stores like Microsoft Excel, dBase, and HTML
COM objects called by a package that are single-threaded
In these situations, ExecuteOnMainThread must be set to True.