We have seen with the release of Fedora 15, the new system is systemd services startup, which will replace sysvinit and Upstart on most Linux distributions. Here are some tips, based on the command systemd-analyze, which can analyze the startup time of your OS.
We start with the time option, which displays the total time you start your system:
$ systemd -analyze time
Startup finished in 6385ms (kernel) + 3228ms (initrd) + 49335ms (userspace) = 58949ms
Here, we start in 59 seconds. It is possible to go further with the option blame, which displays the startup time by service:
$ systemd-analyze blame
The analysis result is very interesting, because we know immediately what services that slow start and we can disable them if they do not serve us.
The last option uses the tip pad and provides a graphical start-up time of each service:
$ systemd-analyze plot > plot.svg
$ eog plot.svg