diff --git a/modules/autosuggestions/external b/modules/autosuggestions/external
index d7c7967..a7f0106 160000
--- a/modules/autosuggestions/external
+++ b/modules/autosuggestions/external
@@ -1 +1 @@
-Subproject commit d7c796719e6352666f7a9c94da9ddaed10f3217d
+Subproject commit a7f0106b31c2538a36cab30428e6ca65d9a2ae60
diff --git a/modules/command-not-found/init.zsh b/modules/command-not-found/init.zsh
index 2c59a4b..bcb0dea 100644
--- a/modules/command-not-found/init.zsh
+++ b/modules/command-not-found/init.zsh
@@ -12,9 +12,28 @@ if [[ -s '/etc/zsh_command_not_found' ]]; then
 # Load command-not-found on Arch Linux-based distributions.
 elif [[ -s '/usr/share/doc/pkgfile/command-not-found.zsh' ]]; then
   source '/usr/share/doc/pkgfile/command-not-found.zsh'
-# Load command-not-found on macOS when homebrew tap is configured.
-elif [[ -s '/usr/local/Homebrew/Library/Taps/homebrew/homebrew-command-not-found/handler.sh' ]]; then
-  source '/usr/local/Homebrew/Library/Taps/homebrew/homebrew-command-not-found/handler.sh'
+# Load command-not-found on macOS when Homebrew tap is configured.
+# To avoid performance penalty, we do not use Homebrew's ruby based command
+# lookup mechanism (viz., `brew command command-not-found-init`) and instead
+# `find` it ourselves from `TAP_DIRECTORY` defined internally in Homebrew.
+elif (( $+commands[brew] )); then
+  cnf_command=("$(brew --repository 2> /dev/null)"/Library/Taps/*/*/cmd/brew-command-not-found-init(|.rb)(.NL+0))
+  if (( $#cnf_command )); then
+    cache_file="${TMPDIR:-/tmp}/prezto-brew-command-not-found-cache.$UID.zsh"
+
+    if [[ "${${(@o)cnf_command}[1]}" -nt "$cache_file" \
+          || "${ZDOTDIR:-$HOME}/.zpreztorc" -nt "$cache_file" \
+          || ! -s "$cache_file" ]]; then
+      # brew command-not-found-init is slow; cache its output.
+      brew command-not-found-init >! "$cache_file" 2> /dev/null
+    fi
+
+    source "$cache_file"
+
+    unset cache_file
+  fi
+
+  unset cnf_command
 # Return if requirements are not found.
 else
   return 1
diff --git a/modules/git/alias.zsh b/modules/git/alias.zsh
index dde5b35..4e4f482 100644
--- a/modules/git/alias.zsh
+++ b/modules/git/alias.zsh
@@ -68,10 +68,11 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   alias gcr='git revert'
   alias gcR='git reset "HEAD^"'
   alias gcs='git show'
+  alias gpS='git show --pretty=short --show-signature'
   alias gcl='git-commit-lost'
   alias gcy='git cherry -v --abbrev'
   alias gcY='git cherry -v'
-
+  
   # Conflict (C)
   alias gCl='git --no-pager diff --name-only --diff-filter=U'
   alias gCa='git add $(gCl)'
@@ -190,6 +191,7 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   alias glg='git log --topo-order --all --graph --pretty=format:"${_git_log_oneline_format}"'
   alias glb='git log --topo-order --pretty=format:"${_git_log_brief_format}"'
   alias glc='git shortlog --summary --numbered'
+  alias glS='git log --show-signature'
 
   # Merge (m)
   alias gm='git merge'
@@ -255,6 +257,8 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   # Tag (t)
   alias gt='git tag'
   alias gtl='git tag -l'
+  alias gts='git tag -s'
+  alias gtv='git verify-tag'
 
   # Working Copy (w)
   alias gws='git status --ignore-submodules=${_git_status_ignore_submodules} --short'
diff --git a/modules/node/init.zsh b/modules/node/init.zsh
index 0a516f0..f452ec5 100644
--- a/modules/node/init.zsh
+++ b/modules/node/init.zsh
@@ -11,8 +11,10 @@ if [[ -s "$HOME/.nvm/nvm.sh" ]]; then
   source "$HOME/.nvm/nvm.sh"
 
 # Load package manager installed NVM into the shell session.
-elif (( $+commands[brew] )) && [[ -d "$(brew --prefix nvm 2> /dev/null)" ]]; then
+elif (( $+commands[brew] )) && \
+  [[ -d "${nvm_prefix::="$(brew --prefix 2> /dev/null)"/opt/nvm}" ]]; then
   source "$(brew --prefix nvm)/nvm.sh"
+  unset nvm_prefix
 
 # Load manually installed nodenv into the shell session.
 elif [[ -s "$HOME/.nodenv/bin/nodenv" ]]; then
@@ -28,18 +30,28 @@ elif (( ! $+commands[node] )); then
   return 1
 fi
 
-# Load NPM completion.
-if (( $+commands[npm] )); then
-  cache_file="${TMPDIR:-/tmp}/prezto-node-cache.$UID.zsh"
+# Load NPM and known helper completions.
+typeset -A compl_commands=(
+  npm   'npm completion'
+  grunt 'grunt --completion=zsh'
+  gupl  'gulp --completion=zsh'
+)
 
-  if [[ "$commands[npm]" -nt "$cache_file" \
-        || "${ZDOTDIR:-$HOME}/.zpreztorc" -nt "$cache_file" \
-        || ! -s "$cache_file" ]]; then
-    # npm is slow; cache its output.
-    npm completion >! "$cache_file" 2> /dev/null
+for compl_command in "${(k)compl_commands[@]}"; do
+  if (( $+commands[$compl_command] )); then
+    cache_file="${TMPDIR:-/tmp}/prezto-$compl_command-cache.$UID.zsh"
+
+    # Completion commands are slow; cache their output if old or missing.
+    if [[ "$commands[$compl_command]" -nt "$cache_file" \
+          || "${ZDOTDIR:-$HOME}/.zpreztorc" -nt "$cache_file" \
+          || ! -s "$cache_file" ]]; then
+      command ${=compl_commands[$compl_command]} >! "$cache_file" 2> /dev/null
+    fi
+
+    source "$cache_file"
+
+    unset cache_file
   fi
+done
 
-  source "$cache_file"
-
-  unset cache_file
-fi
+unset compl_command{s,}
diff --git a/modules/prompt/external/powerlevel9k b/modules/prompt/external/powerlevel9k
index 358c105..2f4b150 160000
--- a/modules/prompt/external/powerlevel9k
+++ b/modules/prompt/external/powerlevel9k
@@ -1 +1 @@
-Subproject commit 358c105de7aa5e8109788adf65c08c44e368d418
+Subproject commit 2f4b15041fe31d85dc9ef705b818c3a0e6985da3
diff --git a/modules/python/init.zsh b/modules/python/init.zsh
index 9796294..d61488e 100644
--- a/modules/python/init.zsh
+++ b/modules/python/init.zsh
@@ -150,7 +150,7 @@ fi
 
 # Load PIP completion.
 if (( $#commands[(i)pip(|[23])] )); then
-  cache_file="${TMPDIR:-/tmp}/prezto-python-cache.$UID.zsh"
+  cache_file="${TMPDIR:-/tmp}/prezto-pip-cache.$UID.zsh"
 
   # Detect and use one available from among 'pip', 'pip2', 'pip3' variants
   pip_command="$commands[(i)pip(|[23])]"
@@ -160,10 +160,11 @@ if (( $#commands[(i)pip(|[23])] )); then
         || ! -s "$cache_file" ]]; then
     # pip is slow; cache its output. And also support 'pip2', 'pip3' variants
     $pip_command completion --zsh \
-      | sed -e "s|compctl -K [-_[:alnum:]]* pip|& pip2 pip3|" >! "$cache_file" 2> /dev/null
+      | sed -e "s|\(compctl -K [-_[:alnum:]]*\) pip.*|\1 pip pip2 pip3|" >! "$cache_file" 2> /dev/null
   fi
 
   source "$cache_file"
+
   unset cache_file pip_command
 fi
 
diff --git a/modules/rsync/init.zsh b/modules/rsync/init.zsh
index 3618812..b3010ed 100644
--- a/modules/rsync/init.zsh
+++ b/modules/rsync/init.zsh
@@ -22,7 +22,7 @@ if grep -q 'xattrs' <(rsync --help 2>&1); then
 fi
 
 # macOS and HFS+ Enhancements
-# http://help.bombich.com/kb/overview/credits#opensource
+# https://bombich.com/kb/ccc5/credits
 if [[ "$OSTYPE" == darwin* ]] && grep -q 'file-flags' <(rsync --help 2>&1); then
   _rsync_cmd="${_rsync_cmd} --crtimes --fileflags --protect-decmpfs --force-change"
 fi
diff --git a/modules/syntax-highlighting/README.md b/modules/syntax-highlighting/README.md
index 7a28892..7a5a30c 100644
--- a/modules/syntax-highlighting/README.md
+++ b/modules/syntax-highlighting/README.md
@@ -9,6 +9,9 @@ Additionally, if this module is used in conjunction with the
 *history-substring-search* module, this module must be loaded **before** the
 *history-substring-search* module.
 
+To elaborate: The relative order of loading the modules would be 
+'syntax-highlighting', 'history-substring-search' and 'prompt'.
+
 Contributors
 ------------