slows down zsh startup time considerably

Created by: sodiumjoe

First off, thanks for autojump!

➤  /usr/bin/time /bin/zsh -i -c exit
        0.50 real         0.37 user         0.11 sys

and with autojump commented out of my .zshrc:

➤  /usr/bin/time /bin/zsh -i -c exit
        0.13 real         0.09 user         0.02 sys

most of the time looks like it's spent calling brew and brew --prefix, so I tried:

.zshrc

# [[ -s $(brew --prefix)/etc/profile.d/autojump.sh ]] && . $(brew --prefix)/etc/profile.d/autojump.sh
[[ -s /usr/local/etc/profile.d/autojump.sh ]] && . /usr/local/etc/profile.d/autojump.sh

and in /usr/local/share/autojump/autojump.zsh (which is $(brew --prefix)/etc/profile.d/autojump.sh):

# set homebrew installation paths
# if command -v brew &>/dev/null && [[ -d "$(brew --prefix)/share/zsh/site-functions" ]]; then
#     fpath=("$(brew --prefix)/share/zsh/site-functions" ${fpath})
# fi
if [[ -d "/usr/local/share/zsh/site-functions" ]]; then
    fpath=("/usr/local/share/zsh/site-functions" ${fpath})
fi

and now:

➤  /usr/bin/time /bin/zsh -i -c exit
        0.13 real         0.09 user         0.03 sys

seems like you could:

1. set an env var on the first brew --prefix
2. let me set the env var myself and skip the brew --prefix entirely
3. skip the command -v brew &>/dev/null since presumably it's redundant with brew --prefix