I reproduced this on Mac OS X 10.7, using both Emacs 22.1.1 and 23.3.1, with no user init file or system init file. Since the original poster produced this on Fedora 5 years ago, I'm guessing this is at least partially OS independent.
Here is a transcript of timing emacs' startup with and without the network turned on:
$ # network adapter is initially on
$ time emacs --kill
real 0m30.108s
user 0m0.076s
sys 0m0.020s
$ time emacs --no-init-file --no-site-file --kill
real 0m30.100s
user 0m0.073s
sys 0m0.020s
$ time emacs --no-init-file --no-site-file --no-window-system --no-desktop --no-splash --kill
real 0m30.118s
user 0m0.080s
sys 0m0.020s
$ # turned off network adapter
$ time emacs --no-init-file --no-site-file --no-window-system --no-desktop --no-splash --kill
real 0m0.105s
user 0m0.079s
sys 0m0.020s
$ # turned on network adapter
$ time emacs --no-init-file --no-site-file --no-window-system --no-desktop --no-splash --kill
real 0m30.106s
user 0m0.079s
sys 0m0.019s
--
Elliott Slaughter
"Don't worry about what anybody else is going to do. The best way to predict the future is to invent it." - Alan Kay