My personal fish shell config for OS X. Supports git branch (fast git checks), virtualenv (if installed) and Kubernetes current context

config.fish

function ls --description 'List contents of directory'
  command ls -lFG $argv
end

function subl --description 'Launches sublime text in a new window'
  command subl -n $argv
end

function code --description 'Launches visual code studio in a new window'
  command code -n $argv
end

function grep --description 'Colorful grep that ignores binary file and outputs line number'
  command grep --color=always -I $argv
end

function gf --description 'Do a git fetch'
  git fetch
end

function gdeletemergedcurrent --wraps git --description 'Delete all local branches that is already merged to current branch (excludes master and main)'
  git branch --merged | grep -v "\*" | grep -v "master" | grip -v "main" | xargs -n 1 git branch -d
  git remote prune origin
end

set -gx GOPATH $HOME/Go
set -gx GOROOT (go env GOROOT)
set PATH $HOME/bin $GOPATH/bin $HOME/.rbenv/shims /usr/local/bin /usr/local/sbin $PATH $GOROOT/bin ./node_modules/.bin

. $HOME/.config/fish/prompt.fish

# set -gx HOMEBREW_GITHUB_API_TOKEN #token here#

# Java
set -gx JAVA_HOME (/usr/libexec/java_home)

# Allow 256 colors in iTerm2 for pretty vim colors
set -gx CLICOLOR 1
set -gx TERM xterm-256color

prompt.fish

# use custom function instead of fish built in git prompt due to performance
# (fish git prompt uses diff which can be slow)
function git_prompt
  set -l git_status_origin (command git status -s -b 2> /dev/null)
  printf ''

  set -l is_repo (string join0 $git_status_origin)

  if test -z $is_repo
    # git status returns error (not a git repo)
    printf ''
  else 
    echo $git_status_origin | string match --regex '\[.*ahead.*\]' --quiet
    set -l ahead $status
    echo $git_status_origin | string match --regex '\[.*behind.*\]' --quiet
    set -l behind $status
    set -l branch (echo $git_status_origin | string replace -r  '## ([\S]+).*' '$1' | string replace -r '(.+)\.\.\..*' '$1')

    # simply check for modified/deleted/rename, match only 1
    echo $git_status_origin | string match --regex '[MDR ][MDR ] .*' --quiet
    set -l git_dirty $status

    # simply check for ?? in the list of files, match only 1
    echo $git_status_origin | string match --regex '\?\? .*' --quiet
    set -l git_untracked $status

    if test "$git_dirty" -eq 0
      printf ' (%s%s' (set_color red)
    else
      printf ' (%s%s' (set_color yellow)
    end

    # Use branch name if available
    if test -n "$branch"
      printf $branch
    else 
      # for new branch, git branch will return nothing, use branch name from git status
      set -l git_status_no_commits_branch (echo $git_status_origin | string replace '## No commits yet on ' '')
      printf $git_status_no_commits_branch
    end

    if test "$git_untracked" -eq 0
      printf '%s*' (set_color purple)
    end

    if test -s .git/refs/stash # stash exists - check on .git/refs/stash file
      printf '%s$' (set_color green)
    end

    # if local repo is ahead, show up arrow
    if test "$ahead" -eq 0
      printf '%s↑' (set_color cyan)
    end

    # if local repo is behind, show down arrow
    if test "$behind" -eq 0
      printf '%s↓' (set_color magenta)
    end
    printf '%s)' (set_color normal)
  end
end

function kubectl_context
  if test -e ~/.kube/config; and type -q kubectl
    set -l current_context (kubectl config current-context)
    printf ' %s[' (set_color normal) 
    printf '%s%s' (set_color cyan) $current_context
    printf '%s]' (set_color normal)
  else
    printf ''
  end
end

function fish_prompt
  # check for iterm2 shell integration
  if test -e {$HOME}/.iterm2_shell_integration.fish ; and source {$HOME}/.iterm2_shell_integration.fish
    printf ' '
  end
  
  printf '%s%s%s' (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
  printf '%s%s ☕️ ' (git_prompt) (kubectl_context)
  set_color normal
end

@henno The issue is with the grep function. Remove it and it's working fine for me

updated git prompt to be much more efficient. Reduces the number of git command calls from 5->1

before

~/w/demo (6.1.1-post*↓) ☕️  time fish_prompt
~/w/demo (6.1.1-post*↓) ☕️
________________________________________________________
Executed in  454.87 millis    fish           external
   usr time   33.16 millis    4.14 millis   29.03 millis
   sys time   69.11 millis   10.09 millis   59.02 millis

~/w/demo (6.1.1-post*↓) ☕️ fish --profile /tmp/profile -c fish_prompt; sort -nk1 /tmp/profile | tail -n 10
270	1434	-> printf '%s%s%s' (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
289	453989	-> printf '%s%s ☕️ ' (git_prompt) (kubectl_context)
562	574	---> source /usr/local/Cellar/fish/3.3.1/share/fish/functions/prompt_pwd.fish
3057	3057	------> command grep --color=always -I $argv
3178	3178	------> command grep --color=always -I $argv
74231	74231	----> git show-ref stash --quiet
77551	77551	-----> git symbolic-ref --short HEAD 2>/dev/null
94570	94570	----> git diff-files --no-ext-diff --quiet
98522	98522	----> command git status -s -b - ^ 2> /dev/null
100950	100950	-----> git ls-files --exclude-standard -o

after

~/w/demo (6.1.1-post*↓) ☕️  time fish_prompt
~/w/demo (6.1.1-post*↓) ☕️
________________________________________________________
Executed in  137.06 millis    fish           external
   usr time   20.18 millis    4.41 millis   15.77 millis
   sys time   33.62 millis    9.83 millis   23.79 millis

~/w/demo (6.1.1-post*↓) ☕️ fish --profile /tmp/profile -c fish_prompt; sort -nk1 /tmp/profile | tail -n 10
131	1255	--> prompt_pwd
135	135	----> string replace -r '^'"$realhome"'($|/)' '~$1' $PWD
210	129566	-> printf '%s%s ☕️ ' (git_prompt) (kubectl_context)
263	1629	-> printf '%s%s%s' (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
787	798	---> source /usr/local/Cellar/fish/3.3.1/share/fish/functions/prompt_pwd.fish
2901	2901	------> command grep --color=always -I $argv
2933	2933	------> command grep --color=always -I $argv
2942	2942	------> command grep --color=always -I $argv
3113	3113	------> command grep --color=always -I $argv
115859	115859	----> command git status -s -b 2> /dev/null

updated to remove all grep calls and use fish' built in string matcher which is faster than grep. Now the bottleneck is only on git status

~/w/demo (6.1.1-post*↓) ☕️ fish --profile /tmp/profile -c fish_prompt; sort -nk1 /tmp/profile | tail -n 10
72	72	----> echo $git_status_origin | string match --regex '\[.*ahead.*\]' --quiet
86	118	---> set -l is_repo (string join0 $git_status_origin)
87	87	--> set_color $fish_color_cwd
112	102796	---> set -l git_status_origin (command git status -s -b 2> /dev/null)
131	131	----> string replace -r '^'"$realhome"'($|/)' '~$1' $PWD
135	712	--> prompt_pwd
198	104113	-> printf '%s%s ☕️ ' (git_prompt) (kubectl_context)
233	246	---> source /usr/local/Cellar/fish/3.3.1/share/fish/functions/prompt_pwd.fish
265	1082	-> printf '%s%s%s' (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
102684	102684	----> command git status -s -b 2> /dev/null

upgraded to latest git and it's even faster now

~/w/demo (6.1.1-post*↓) ☕️  fish --profile /tmp/profile-oldgit -c fish_prompt; sort -nk2 /tmp/profile-oldgit | tail -n 10
64        200     ---> set -l tmp (string replace -r '^'"$realhome"'($|/)' '~$1' $PWD)
274     285     ---> source /usr/local/Cellar/fish/3.3.1/share/fish/functions/prompt_pwd.fish
151     768     --> prompt_pwd
48      867     ---> if test -z $is_repo...
272     1151    -> printf '%s%s%s' (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
40040   40040   ----> command git status -s -b 2> /dev/null
111     40151   ---> set -l git_status_origin (command git status -s -b 2> /dev/null)
27      41174   --> git_prompt
200     41435   -> printf '%s%s ☕️ ' (git_prompt) (kubectl_context)
23      42659   > fish_prompt

Fixed git prompt for repo without origin