Prompt to open file literally when opening large files.

core/core-dotspacemacs.el

@@ -176,6 +176,10 @@ start.")
 (defvar dotspacemacs-helm-position 'bottom
   "Position in which to show the `helm' mini-buffer.")
 
+(defvar dotspacemacs-large-file-size 1
+  "Size (in MB) above which spacemacs will prompt to open literally to avoid
+  performance issues.")
+
 (defvar dotspacemacs-auto-save-file-location 'cache
   "Location where to auto-save files. Possible values are `original' to
 auto-save the file in-place, `cache' to auto-save the file to another

core/templates/.spacemacs.template

@@ -149,6 +149,9 @@ values."
    ;; If non nil then the last auto saved layouts are resume automatically upon
    ;; start. (default nil)
    dotspacemacs-auto-resume-layouts nil
+   ;; Buffer file size (in MB), above which spacemacs will prompt to open the
+   ;; buffer literally to improve performance. (default 1)
+   dotspacemacs-large-file-size 1
    ;; Location where to auto-save files. Possible values are `original' to
    ;; auto-save the file in-place, `cache' to auto-save the file to another
    ;; file stored in the cache directory and `nil' to disable auto-saving.

layers/+distribution/spacemacs-base/config.el

@@ -161,6 +161,9 @@ It runs `tabulated-list-revert-hook', then calls `tabulated-list-print'."
 (with-eval-after-load 'comint
   (define-key comint-mode-map (kbd "C-d") nil))
 
+;; Prompt to open file literally if large file.
+(add-hook 'find-file-hook 'spacemacs/check-large-file)
+
 ;; whitespace-cleanup configuration
 (pcase dotspacemacs-whitespace-cleanup
   (`all (add-hook 'before-save-hook 'whitespace-cleanup))

layers/+distribution/spacemacs-base/funcs.el

@@ -327,6 +327,15 @@ argument takes the kindows rotate backwards."
               (buffer-string)))
            (t (concat "/sudo:root@localhost:" fname))))))
 
+;; check when opening large files - literal file open
+(defun spacemacs/check-large-file ()
+  (when (> (nth 7 (file-attributes (buffer-file-name)))
+           (* 1024 1024 dotspacemacs-large-file-size))
+    (when (y-or-n-p "This is a large file, open literally to avoid performance issues?")
+      (setq buffer-read-only t)
+      (buffer-disable-undo)
+      (fundamental-mode))))
+
 ;; found at http://emacswiki.org/emacs/KillingBuffers
 (defun spacemacs/kill-other-buffers ()
   "Kill all other buffers."