Environment: Boost1.47 + Microsoft HPC 2008 SDK I find Delta Stepping Dijkstra and Crauser Dijkstra in boost, and both of them are slower than sequential dijkstra in boost. (About 10 times slower. I used 10 graphs, the biggest graph contains 10 million nodes and 10 million edges) Q1: I wonder why the parallel dijkstra is slower than sequential version? Q2: Can I adjust the number of threads that Delta Stepping used? (For exemple, I want it use 1, 2, 3, 4 threads respectively. And Can I make it sequential version?) Thx --- Chen Kai School of Computer Science, Fudan University blog: http://www.cnblogs.com/remlostime/