Comment & further optimize so-long-mode

core/core-editor.el

@@ -461,10 +461,17 @@ files, so we replace calls to `pp' with the much faster `prin1'."
   :after-call after-find-file
   :config
   (global-so-long-mode +1)
+  ;; Don't disable syntax highlighting or line numbers in so-long-mode, so we
+  ;; can have a basic editing experience in them, at least.
   (delq! 'font-lock-mode so-long-minor-modes)
   (delq! 'display-line-numbers-mode so-long-minor-modes)
+  ;; ...but reduce the level of syntax highlighting
+  (add-to-list 'so-long-variable-overrides '(font-lock-maximum-decoration . 1))
+  ;; But disable everything else that may be unnecessary/expensive for large
+  ;; or wide buffers.
   (appendq! so-long-minor-modes
             '(flycheck-mode
+              flyspell-mode
               eldoc-mode
               smartparens-mode
               highlight-numbers-mode