The size difference was based on my intuition that when I maintained my own .bashrc and .zshrc, I was able to "get away" with fewer total lines in my .zshrc than my .bashrc. I remember my .bashrc being dozens of pages, my .zshrc was only a couple.
Compare that to my fish init file...all it does is set a few paths and aliases and turn off the greeting, because everything else just works out of the box for me.
$ ls -lh .bashrc
-rw-r--r-- 1 <me> <me> 10k Jul 26 13:31 .bashrc
It's also remarkably fast because I took great effort to optimize the parts that happen the most. Shell is actually pretty fast if you don't fork and exec all the time...
add_to PATH /usr/sbin
prefix() {
replace_in PATH "$1/bin"
replace_in PATH "$1/sbin"
replace_in PATH "$1/lib/ccache"
replace_in MANPATH "$1/share/man"
replace_in MANPATH "$1/man"
replace_in PKG_CONFIG_PATH "$1/lib/pkgconfig"
...etc.
prefix /usr/local
prefix /usr/local/brew
prefix /usr/local/ports
All that stuff is the part I optimized so that it only uses bash built-ins and never execs. Converting that away from sed/perl shaved about 8 seconds off my startup time (it's now so fast I don't notice it).
The next 20% is interactive stuff. Setting up the prompt, aliases, stty, etc. This is generally more complicated than it technically needs to be because it's cross platform so it'll run on any unix-y thing with no changes.
Then remaining 40% is a big chunk of shell functions that are mostly unused in my day-to-day life, but kept there to jog my memory if I need to do a certain task.
That adds up to 100%, but it's also worth noting that 27% of that is blank lines and comments.
$ cd bash-it
$ sloccount ./
...SNIP...
SLOC Directory SLOC-by-Language (Sorted)
3198 completion sh=3198
3168 plugins sh=3168
1081 themes sh=1081
748 lib sh=748
242 aliases sh=242
135 top_dir sh=135
16 template sh=16
0 custom (none)
Totals grouped by language (dominant language first):
sh: 8588 (100.00%)
edited to reflect distinction between parent and grandparent comment