Simplify and decouple init files

The two doom-gc-* variables in init.el couples the rest of the config to
these two files. The bulk of GC/file-handler optimization was moved into
core.el and simplified (all that idle-timer voodoo was overkill).

Also adds (setq frame-inhibit-implied-reize t) to early-init, which
speeds up startup a fair bit in some edge cases with larger fonts.

squash! Simplify and decouple init files

init.el

@@ -27,61 +27,23 @@
 ;;
 ;;; License: MIT
 
-(defvar doom-gc-cons-threshold 16777216 ; 16mb
-  "The default value to use for `gc-cons-threshold'. If you experience freezing,
-decrease this. If you experience stuttering, increase this.")
-
-(defvar doom-gc-cons-upper-limit 536870912 ; 512mb
-  "The temporary value for `gc-cons-threshold' to defer it.")
-
-
-(defvar doom--file-name-handler-alist file-name-handler-alist)
-
-(defun doom-restore-startup-optimizations-h ()
-  "Resets garbage collection settings to reasonable defaults (a large
-`gc-cons-threshold' can cause random freezes otherwise) and resets
-`file-name-handler-alist'."
-  (setq file-name-handler-alist doom--file-name-handler-alist)
-  ;; Do this on idle timer to defer a possible GC pause that could result; also
-  ;; allows deferred packages to take advantage of these optimizations.
-  (run-with-idle-timer
-   3 nil
-   (lambda ()
-     (setq-default gc-cons-threshold doom-gc-cons-threshold)
-     ;; To speed up minibuffer commands (like helm and ivy), we defer garbage
-     ;; collection while the minibuffer is active.
-     (defun doom-defer-garbage-collection-h ()
-       (setq gc-cons-threshold doom-gc-cons-upper-limit))
-     (defun doom-restore-garbage-collection-h ()
-       ;; Defer it so that commands launched from the minibuffer can enjoy the
-       ;; benefits.
-       (run-at-time 1 nil (lambda () (setq gc-cons-threshold doom-gc-cons-threshold))))
-     (add-hook 'minibuffer-setup-hook #'doom-defer-garbage-collection-h)
-     (add-hook 'minibuffer-exit-hook  #'doom-restore-garbage-collection-h)
-     ;; GC all sneaky breeky like
-     (add-hook 'focus-out-hook #'garbage-collect))))
-
-
-(if (ignore-errors (or after-init-time noninteractive))
-    (setq gc-cons-threshold doom-gc-cons-threshold)
-  ;; A big contributor to startup times is garbage collection. We up the gc
-  ;; threshold to temporarily prevent it from running, then reset it later in
-  ;; `doom-restore-startup-optimizations-h'.
-  (setq gc-cons-threshold doom-gc-cons-upper-limit)
-  ;; This is consulted on every `require', `load' and various path/io functions.
-  ;; You get a minor speed up by nooping this.
-  (setq file-name-handler-alist nil)
-  ;; Not restoring these to their defaults will cause stuttering/freezes.
-  (add-hook 'after-init-hook #'doom-restore-startup-optimizations-h))
-
+(when (version< emacs-version "25.3")
+  (error "Detected Emacs %s. Doom only supports Emacs 25.3 and higher"
+         emacs-version))
 
 ;; Ensure Doom is running out of this file's directory
 (setq user-emacs-directory (file-name-directory load-file-name))
-;; In noninteractive sessions, prioritize non-byte-compiled source files to
-;; prevent stale, byte-compiled code from running. However, if you're getting
-;; recursive load errors, it may help to set this to nil.
-(setq load-prefer-newer noninteractive)
 
+;; A big contributor to startup times is garbage collection. We up the gc
+;; threshold to temporarily prevent it from running, then reset it later with
+;; `doom-restore-garbage-collection-h'. Not resetting it will cause
+;; stuttering/freezes.
+(setq gc-cons-threshold most-positive-fixnum)
+
+;; In noninteractive sessions, prioritize non-byte-compiled source files to
+;; prevent the use of stale byte-code. Otherwise, it saves us a little IO time
+;; to skip the mtime checks on every *.elc file we load.
+(setq load-prefer-newer noninteractive)
 
 ;; Let 'er rip!
 (require 'core (concat user-emacs-directory "core/core"))