Hello,

This is my configuration for completion-preview:

(use-package completion-preview
  :hook (after-init . global-completion-preview-mode)
  :bind (:map completion-preview-active-mode-map
              ("M-n" . completion-preview-next-candidate)
              ("M-p" . completion-preview-prev-candidate))
  :custom (completion-preview-idle-delay 0.2)
  :config
  ;; Org mode has a custom `self-insert-command'
  (push 'org-self-insert-command completion-preview-commands)

  ;; Hide `completion-preview' overlay when invoking `completion-in-region'
  (with-eval-after-load 'consult
    (advice-add 'consult-completion-in-region :before (lambda (&rest _) (completion-preview-hide)))))

When I enter org-mode file and flyspell-mode is toggled on then the
completion-preview-idle-delay is much longer in reality that 0.2s. After
I disable flyspell-mode, then the delay is truly 0.2s. It
seems that completion-preview is being delayed by flyspell checking
currently written word. It makes sense if we consider 'idle' literally,
but I'm not sure if this is desired.

In GNU Emacs 30.0.92 (build 1, x86_64-redhat-linux-gnu, GTK+ Version
 3.24.43, cairo version 1.18.0) of 2024-11-19 built on
 f37c2cd00c6a4c8fbc0fa73e20903c45
System Description: Fedora Linux 41 (Toolbx Container Image)

Configured using:
 'configure --build=x86_64-redhat-linux --host=x86_64-redhat-linux
 --program-prefix= --disable-dependency-tracking --prefix=/usr
 --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin
 --sysconfdir=/etc --datadir=/usr/share --includedir=/usr/include
 --libdir=/usr/lib64 --libexecdir=/usr/libexec --localstatedir=/var
 --runstatedir=/run --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-cairo --with-dbus --with-gif
 --with-gpm=no --with-harfbuzz --with-jpeg --with-modules
 --with-native-compilation=aot --with-pgtk --with-png --with-rsvg
 --with-sqlite3 --with-tiff --with-tree-sitter --with-webp --with-xpm
 build_alias=x86_64-redhat-linux host_alias=x86_64-redhat-linux CC=gcc
 'CFLAGS=-DMAIL_USE_LOCKF -O2 -flto=auto -ffat-lto-objects -fexceptions
 -g -grecord-gcc-switches -pipe -Wall -Werror=format-security
 -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -march=x86-64
 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection
 -fcf-protection -mtls-dialect=gnu2 -fno-omit-frame-pointer
 -mno-omit-leaf-frame-pointer ' 'LDFLAGS=-Wl,-z,relro -Wl,--as-needed
 -Wl,-z,pack-relative-relocs -Wl,-z,now
 -specs=/usr/lib/rpm/redhat/redhat-hardened-ld
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1
 -specs=/usr/lib/rpm/redhat/redhat-package-notes ' CXX=g++ 'CXXFLAGS=-O2
 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches
 -pipe -Wall -Werror=format-security
 -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -march=x86-64
 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection
 -fcf-protection -mtls-dialect=gnu2 -fno-omit-frame-pointer
 -mno-omit-leaf-frame-pointer '
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY
PDUMPER PGTK PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XIM GTK3 ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Org

Minor modes in effect:
  denote-menu-bar-mode: t
  flyspell-mode: t
  rcirc-track-minor-mode: t
  server-mode: t
  recentf-mode: t
  savehist-mode: t
  save-place-mode: t
  repeat-mode: t
  global-subword-mode: t
  subword-mode: t
  delete-selection-mode: t
  electric-pair-mode: t
  pixel-scroll-precision-mode: t
  global-auto-revert-mode: t
  vertico-mode: t
  marginalia-mode: t
  global-completion-preview-mode: t
  completion-preview-mode: t
  diff-hl-margin-local-mode: t
  diff-hl-margin-mode: t
  global-diff-hl-mode: t
  diff-hl-mode: t
  global-treesit-auto-mode: t
  minibuffer-electric-default-mode: t
  minibuffer-depth-indicate-mode: t
  popper-echo-mode: t
  popper-mode: t
  windmove-mode: t
  override-global-mode: t
  apheleia-global-mode: t
  apheleia-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tab-bar-history-mode: t
  tab-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  visual-line-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
/var/home/alternateved/.config/emacs/elpa/transient-20241115.2034/transient hides /usr/share/emacs/30.0.92/lisp/transient

Features:
(shadow sort mail-extr misearch multi-isearch dired-aux hl-line denote
xref emacsbug cl-print vertico-directory completion help-fns radix-tree
puni pulse color mule-util orderless dabbrev tempel apheleia
apheleia-rcs apheleia-dp apheleia-formatters apheleia-utils apheleia-log
apheleia-formatter-context embark-org embark-consult embark ffap vc-git
cape oc-basic org-element org-persist org-id org-refile org-element-ast
inline avl-tree generator ol-eww eww xdg url-queue mm-url ol-rmail
ol-mhe ol-irc ol-info ol-gnus nnselect gnus-art mm-uu mml2015 mm-view
mml-smime smime dig gnus-sum shr pixel-fill kinsoku url-file svg dom
gnus-group gnus-undo gnus-start gnus-dbus dbus xml gnus-cloud nnimap
nnmail mail-source utf7 nnoo gnus-spec gnus-int gnus-range message
sendmail yank-media rfc822 mml mml-sec mm-decode mm-bodies mm-encode
mail-parse rfc2231 rfc2047 rfc2045 ietf-drums mailabbrev gmm-utils
mailheader gnus-win gnus nnheader gnus-util mail-utils range mm-util
mail-prsvr ol-docview doc-view jka-compr image-mode exif ol-bibtex
bibtex ol-bbdb ol-w3m ol-doi org-link-doi org ob ob-tangle ob-ref ob-lob
ob-table ob-exp org-macro org-src sh-script smie executable ob-comint
org-pcomplete pcomplete org-list org-footnote org-faces org-entities
org-version ob-emacs-lisp ob-core ob-eval org-cycle org-table ol
org-fold org-fold-core org-keys oc org-loaddefs find-func cal-menu
calendar cal-loaddefs org-compat org-macs format-spec comp comp-cstr
comp-run comp-common rx cursor-sensor vertico-repeat consult bookmark
flyspell ispell gnutls network-stream puny nsm rcirc epa-file epa
derived epg rfc6068 epg-config parse-time iso8601 cus-start server
noutline outline time-date checkdoc lisp-mnt flymake project compile
text-property-search comint ansi-osc ansi-color warnings thingatpt
recentf tree-widget savehist saveplace repeat cap-words superword
subword delsel elec-pair pixel-scroll cua-base ring autorevert
filenotify vertico marginalia compat completion-preview
exec-path-from-shell diff-hl-margin diff-hl-dired dired dired-loaddefs
diff-hl log-view pcvs-util vc-dir ewoc vc vc-dispatcher diff-mode
track-changes flymake-collection-hook treesit-auto treesit minibuf-eldef
mb-depth popper-echo popper windmove modus-operandi-theme modus-themes
disp-table advice edmacro kmacro use-package use-package-ensure
use-package-delight use-package-diminish use-package-bind-key bind-key
cl-extra help-mode use-package-core finder-inf ajrepl-autoloads
apheleia-autoloads avy-autoloads cape-autoloads consult-dir-autoloads
corfu-terminal-autoloads corfu-autoloads denote-autoloads
diff-hl-autoloads dts-mode-autoloads eat-autoloads
edit-indirect-autoloads elfeed-autoloads embark-consult-autoloads
consult-autoloads embark-autoloads exec-path-from-shell-autoloads
flymake-collection-autoloads geiser-guile-autoloads geiser-autoloads
gptel-autoloads haskell-mode-autoloads janet-ts-mode-autoloads
ledger-mode-autoloads lingva-autoloads magit-autoloads pcase
magit-section-autoloads marginalia-autoloads markdown-mode-autoloads
olivetti-autoloads orderless-autoloads pcmpl-args-autoloads
popon-autoloads popper-autoloads puni-autoloads easy-mmode
purescript-mode-autoloads rainbow-mode-autoloads sly-autoloads
smartparens-autoloads dash-autoloads tempel-autoloads
transient-autoloads treesit-auto-autoloads vertico-autoloads
vundo-autoloads web-mode-autoloads wgrep-autoloads info
with-editor-autoloads xclip-autoloads package browse-url url url-proxy
url-privacy url-expand url-methods url-history url-cookie
generate-lisp-file url-domsuf url-util mailcap url-handlers url-parse
auth-source cl-seq eieio eieio-core cl-macs password-cache json subr-x
map byte-opt bytecomp byte-compile url-vars gv cus-edit pp cus-load
icons wid-edit cl-loaddefs cl-lib rmc iso-transl tooltip cconv eldoc
paren electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode
mwheel term/pgtk-win pgtk-win term/common-win touch-screen pgtk-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 dbusbind
inotify dynamic-setting system-font-setting font-render-setting cairo
gtk pgtk multi-tty move-toolbar make-network-process native-compile
emacs)

Memory information:
((conses 16 736317 667463) (symbols 48 41370 4) (strings 32 204409 35035)
 (string-bytes 1 6531566) (vectors 16 68015) (vector-slots 8 1503632 408280)
 (floats 8 602 7069) (intervals 56 3248 2681) (buffers 992 28))