Early Initialization

Table of Contents

The early-init.el file is loaded before the package system and GUI is initialized. This is the perfect place for performance optimizations and settings that must be applied before any packages load.

1. Why Early Init?

Emacs 27+ introduced early-init.el which loads before:

  • Package initialization
  • GUI frame creation
  • Custom file loading

This allows us to:

  • Maximize startup performance
  • Prevent visual flash/flicker
  • Configure native compilation before packages load

2. Native Compilation Setup

Modern Emacs supports native compilation of Emacs Lisp to machine code for better performance. On macOS with Homebrew, we need to configure the GCC library paths.

2.1. How It Works

  1. Checks if native compilation is available
  2. On macOS, locates the Homebrew GCC installation
  3. Sets up LIBRARY_PATH for the linker
  4. Configures native-comp-driver-options to find GCC libraries
  5. Enables async compilation with minimal warnings
;;; early-init.el --- Emacs-Solo (no external packages) Configuration  -*- lexical-binding: t; -*-
;;; Commentary:
;; Early init configuration for Emacs-Solo
;;; Code:

;; Native compilation settings - must come before any packages load
(when (and (fboundp 'native-comp-available-p)
           (native-comp-available-p))
  (when (eq system-type 'darwin)
    ;; macOS with Homebrew GCC: Set up library paths
    ;; The library is in: /opt/homebrew/lib/gcc/current/gcc/aarch64-apple-darwin24/VERSION/
    (let* ((gcc-base "/opt/homebrew/lib/gcc/current/gcc")
           (arch-dir (expand-file-name "aarch64-apple-darwin24" gcc-base))
           (version-dirs (when (file-directory-p arch-dir)
                          (directory-files arch-dir t "^[0-9]+" t)))
           (gcc-lib-dir (when version-dirs (car version-dirs))))
      (when gcc-lib-dir
        ;; Set LIBRARY_PATH for the linker
        (setenv "LIBRARY_PATH"
                (concat gcc-lib-dir ":"
                        "/opt/homebrew/lib/gcc/current:"
                        (or (getenv "LIBRARY_PATH") "")))
        ;; Configure native-comp to use this GCC
        (setq native-comp-driver-options
              (list (concat "-B" gcc-lib-dir)
                    (concat "-L" gcc-lib-dir)
                    "-B/opt/homebrew/lib/gcc/current"
                    "-L/opt/homebrew/lib/gcc/current")))))

  ;; General native compilation settings
  (setq native-comp-async-report-warnings-errors nil
        native-comp-deferred-compilation t))

3. Startup Performance Optimizations

These settings dramatically improve Emacs startup time by deferring expensive operations until after initialization.

3.1. Garbage Collection

We temporarily disable garbage collection during startup by setting gc-cons-threshold to maximum. This prevents GC pauses during the critical startup phase.

Note: We should reset this in init.el after startup completes (typically to 16MB).

3.2. Version Control

We limit vc-handled-backends to only Git, skipping checks for other VCS systems we don't use. 

;; Startup hacks
(setq gc-cons-threshold most-positive-fixnum
        gc-cons-percentage 0.6
        vc-handled-backends '(Git))

4. Prevent Visual Flash

When Emacs starts, there's often a brief flash of the default theme before your custom theme loads. This function prevents that by:

  • Hiding the mode line temporarily
  • Optionally setting background/foreground to match your theme
;; Hack to avoid being flashbanged
(defun emacs-solo/avoid-initial-flash-of-light ()
  "Avoid flash of light when starting Emacs."
  (setq mode-line-format nil)
  ;; These colors should match your selected theme for maximum effect
  ;; Note that for catppuccin whenever we create a new frame or open it on terminal
  ;; it is necessary to reload the theme.
  ;; (set-face-attribute 'default nil :background "#292D3E" :foreground "#292D3E")
  )

(emacs-solo/avoid-initial-flash-of-light)

5. Frame Configuration

Configure frame (window) behavior before the GUI initializes:

  • frame-resize-pixelwise - Allow pixel-precise frame sizing (not just character-grid)
  • frame-inhibit-implied-resize - Prevent unexpected frame resizing during startup
  • frame-title-format - Set window title to just "Emacs"
;; Better Window Management handling
(setq frame-resize-pixelwise t
        frame-inhibit-implied-resize t
        frame-title-format '("Emacs"))

(setq inhibit-compacting-font-caches t)

6. Disable Unused UI Elements

Remove visual clutter and improve performance by disabling UI elements we don't need:

  • menu-bar-mode - The File/Edit/View menu at top
  • scroll-bar-mode - Graphical scroll bars
  • tool-bar-mode - Icon toolbar (usually with New/Open/Save icons)
  • tooltip-mode - Popup tooltips

These are disabled early to prevent them from being drawn and then hidden, which saves startup time. 

;; Disables unused UI Elements
(menu-bar-mode 0)
(scroll-bar-mode 0)
(tool-bar-mode 0)
(tooltip-mode 0)

;; Resizing the Emacs frame can be a terribly expensive part of changing the
;; font. By inhibiting this, we easily halve startup times with fonts that are
;; larger than the system default.
(setq frame-inhibit-implied-resize t
        frame-resize-pixelwise t)

(provide 'early-init)
;;; early-init.el ends here