Saving a small file in emacs -q seems to take 1  to 5 seconds.

I assume this because the 'Rapid Refresh' app I am using takes 1 to 5
seconds to notice
the file change when I change it with emacs but 0 seconds when changed with
another editor.
.
I have done a recent and fresh install of emacs to see if it fixed it but
had no luck.

# set up rapid refresh app
npx create-expo-app@latest -t tabs@50
cd my-app
npx expo start
w
http://localhost:8082/

emacs -q 'app/(tabs)/index.tsx'
;; added a letter to a welcome string.
M-x save-buffer

Expected result:  the 'Fast Refresh' of expo should instantly update
the web page.

Actual result: a variable 1 to 6 second delay (repeating same process)
before update

Actual result with neovim: page save leads to instant update every time.

I tried disabling these with no effect on the time

 (setq before-save-hook nil)
 (setq after-save-hook nil)
 (setq vc-handled-backends nil)

I profiled save-buffer and it was
'0 0% ...'



In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.37, cairo version 1.16.0) of 2023-05-13 built on no-control-x1c
Repository revision: 7791907c3852e6ec197352e1c3d3dd8487cc04f5
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12302000
System Description: Ubuntu 23.10

Configured using:
 'configure --with-tree-sitter --with-mailutils --with-json
 --with-xwidgets --with-modules --with-imagemagick
 --prefix=/home/no-control/installs --bindir=/home/no-control/bin
 --with-native-compilation=no --with-xft'

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ IMAGEMAGICK
JPEG JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM XINPUT2 XPM XWIDGETS
GTK3 ZLIB

Important settings:
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util text-property-search mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils extra-functions
thingatpt help-fns radix-tree cl-print byte-opt gv bytecomp byte-compile
debug backtrace help-mode find-func profiler time-date subr-x
cl-loaddefs cl-lib rmc iso-transl tooltip cconv eldoc paren electric
uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads xwidget-internal dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit xinput2 x multi-tty
make-network-process emacs)

Memory information:
((conses 16 55658 12506)
 (symbols 48 6603 0)
 (strings 32 18066 1619)
 (string-bytes 1 523080)
 (vectors 16 52241)
 (vector-slots 8 1066424 14413)
 (floats 8 38 50)
 (intervals 56 663 0)
 (buffers 984 18))