Hi, I am using mpich-1.4.1.p1 to launch multiple child processes. On Window Server 2008 all the child processes are launched almost immediately but this takes significant time on Window Server 2012. I am using MPI_Comm_spawn for spawning a process and MPI::Init_thread(argc,argv,MPI_THREAD_MULTIPLE) is used for initializing MPICH2. Please let me know if this is a known problem. Is there any workaround ? Regards, Abhishek