Hi, We no longer support use of MPICH on Windows. We encourage users to try MS-MPI. https://docs.microsoft.com/en-us/message-passing-interface/microsoft-mpi Ken On 6/15/21, 8:07 PM, "ZJ CHEN via discuss" <[email protected]> wrote: My OS: windows10mpich2: 1.3-32bit and 1.5-64bit I install both versions successfully, and I test the MPIEXEC -N 10 CPI.EXE example. It works, but with a very slow launching duration of about 4 minutes. How can I fix this problem? Thanks for any help! ZHIJUN