org-mode: Initialise cache before initialising file-local regexps

* lisp/org.el (org-mode): Initialise cache earlier, allowing the
file-local settings to be taken from persistent cache when
possible.  Also, bind `org-mode-loading' while org-mode is loading.
* lisp/ol.el (org-update-radio-target-regexp): Do not try to refresh
cache when we are loading file for the first time.

lisp/ol.el

@@ -2020,7 +2020,8 @@ Also refresh fontification if needed."
 				    (list old-regexp org-target-link-regexp)
 				    "\\|")
 				   after-re)))))
-	(when (featurep 'org-element)
+	(when (and (featurep 'org-element)
+                   (not (bound-and-true-p org-mode-loading)))
 	  (org-with-point-at 1
 	    (while (re-search-forward regexp nil t)
 	      (org-element-cache-refresh (match-beginning 1))))))

lisp/org.el

@@ -4820,6 +4820,8 @@ This is for getting out of special buffers like capture.")
 
 (defvar org-element-cache-persistent); Defined in org-element.el
 (defvar org-element-use-cache); Defined in org-element.el
+(defvar org-mode-loading nil
+  "Non-nil during Org mode initialisation.")
 ;;;###autoload
 (define-derived-mode org-mode outline-mode "Org"
   "Outline-based notes management and organizer, alias
@@ -4839,6 +4841,7 @@ can be exported as a structured ASCII or HTML file.
 The following commands are available:
 
 \\{org-mode-map}"
+  (setq-local org-mode-loading t)
   (org-load-modules-maybe)
   (org-install-agenda-files-menu)
   (when org-link-descriptive (add-to-invisibility-spec '(org-link)))
@@ -4874,6 +4877,11 @@ The following commands are available:
   (add-hook 'before-change-functions 'org-before-change-function nil 'local)
   ;; Check for running clock before killing a buffer
   (add-hook 'kill-buffer-hook 'org-check-running-clock nil 'local)
+  ;; Initialize cache.
+  (org-element-cache-reset)
+  (when (and org-element-cache-persistent
+             org-element-use-cache)
+    (org-persist-read 'org-element--cache (current-buffer)))
   ;; Initialize macros templates.
   (org-macro-initialize-templates)
   ;; Initialize radio targets.
@@ -4885,11 +4893,6 @@ The following commands are available:
   (org-setup-filling)
   ;; Comments.
   (org-setup-comments-handling)
-  ;; Initialize cache.
-  (org-element-cache-reset)
-  (when (and org-element-cache-persistent
-             org-element-use-cache)
-    (org-persist-read 'org-element--cache (current-buffer)))
   ;; Beginning/end of defun
   (setq-local beginning-of-defun-function 'org-backward-element)
   (setq-local end-of-defun-function
@@ -4978,7 +4981,8 @@ The following commands are available:
   ;; Set face extension as requested.
   (org--set-faces-extend '(org-block-begin-line org-block-end-line)
                          org-fontify-whole-block-delimiter-line)
-  (org--set-faces-extend org-level-faces org-fontify-whole-heading-line))
+  (org--set-faces-extend org-level-faces org-fontify-whole-heading-line)
+  (setq-local org-mode-loading nil))
 
 ;; Update `customize-package-emacs-version-alist'
 (add-to-list 'customize-package-emacs-version-alist