Jessie: How to reduce time of "networking.service" when booting up

Hello Debian users,

When I type command "systemd-analyze blame", it takes long time in networking.service.

Does anyone know how to reduce time of networking.service?

1.216s networking.service
406ms systemd-udev-trigger.service
246ms systemd-tmpfiles-setup.service
190ms systemd-readahead-replay.service
180ms kmod-static-nodes.service
153ms systemd-sysctl.service
123ms systemd-logind.service
118ms systemd-update-utmp.service

The following may be more useful here as it will show units holding up the starting of other units etc

systemd-analyze critical-chain