Move startup optimization to early-init

Also load early-init from init if early-init-file isn't bound. This
improves startup a modest 3-5% for Emacs 27 users.

init.el

@@ -27,42 +27,7 @@
 ;;
 ;;; License: MIT
 
-;; Ensure Doom is always running out of this file's directory
-(setq user-emacs-directory (file-name-directory load-file-name)
-      load-prefer-newer noninteractive)
-
-
-;;
-;; Optimize startup
-;;
-
-(unless noninteractive
-  (defvar doom--file-name-handler-alist
-    file-name-handler-alist)
-  (unless after-init-time
-    ;; A big contributor to long startup times is the garbage collector, so we
-    ;; up its memory threshold, temporarily and reset it later in
-    ;; `doom|finalize'.
-    (setq gc-cons-threshold 402653184
-          gc-cons-percentage 1.0
-          ;; consulted on every `require', `load' and various file reading
-          ;; functions. You get a minor speed up by nooping this.
-          file-name-handler-alist nil))
-
-  (defun doom|finalize ()
-    "Resets garbage collection settings to reasonable defaults (if you don't do
-this, you'll get stuttering and random freezes) and resets
-`file-name-handler-alist'."
-    (setq file-name-handler-alist doom--file-name-handler-alist
-          gc-cons-threshold 16777216
-          gc-cons-percentage 0.2))
-
-  (add-hook 'emacs-startup-hook #'doom|finalize)
-  (add-hook 'doom-reload-hook   #'doom|finalize))
-
-
-;;
-;; Bootstrap Doom
-;;
+(unless (boundp 'early-init-file)
+  (load (concat (file-name-directory load-file-name) "early-init")))
 
 (require 'core (concat user-emacs-directory "core/core"))