After I reinstall the CentOS 7.4, Salome 8.3.0 starts slowly in about one minute. The problem may be caused by the conflict of network.service and NetworkManager.service. The possible solution is
sudo systemctl disable network.service sudo systemctl stop network.service reboot
Because network.service does not work on my machine, it should be disabled.
Then Salome 8.3.0 starts in one second.
This also can solve the problem that ParaView 4.0.1 starts slowly.
But after several runs, salome and paraview run slowly again.
Then reset all network settings, it solves the problem. NetworkManager.service and network.service work well together.