Fix slowness of the 'follow-cursor' feature

* eldoc-box.el (eldoc-box--inhibit-childframe-timer): Remove
variable.
(eldoc-box--inhibit-childframe-for): Refactor to use
'run-with-idle-timer' instead of 'run-with-timer'
(eldoc-box--follow-cursor): Don't do anything if the timer is set

eldoc-box.el

@@ -317,29 +317,24 @@ FRAME is the childframe, WINDOW is the primary window."
     ;; move position
     (set-frame-position frame (car pos) (cdr pos))))
 
-(defvar eldoc-box--inhibit-childframe-timer nil
-  "When this timer is on, inhibit childframe display.
-Intended for follow-cursor to disable display when moving cursor.")
-
 (defun eldoc-box--inhibit-childframe-for (sec)
-  "Inhibit display of childframe for SEC seconds."
-  (when eldoc-box--inhibit-childframe-timer
-    (cancel-timer eldoc-box--inhibit-childframe-timer))
+  "Inhibit display of childframe for SEC seconds after Emacs is idle again."
+  (unless eldoc-box--inhibit-childframe
+    (setq eldoc-box--inhibit-childframe t)
     (eldoc-box-quit-frame)
-  (setq eldoc-box--inhibit-childframe t
-        eldoc-box--inhibit-childframe-timer
-        (run-with-timer sec nil
+    (run-with-idle-timer sec nil
                     (lambda ()
                       (setq eldoc-box--inhibit-childframe nil)))))
 
 (defun eldoc-box--follow-cursor ()
   "Make childframe follow cursor in at-point mode."
+  (unless eldoc-box--inhibit-childframe
     (if (member this-command eldoc-box-self-insert-command-list)
         (progn (when (frame-live-p eldoc-box--frame)
                  (eldoc-box--update-childframe-geometry
                   eldoc-box--frame (frame-selected-window eldoc-box--frame))))
       ;; if not typing, inhibit display
-    (eldoc-box--inhibit-childframe-for 0.2)))
+      (eldoc-box--inhibit-childframe-for 0.5))))
 
 (defun eldoc-box--get-frame (buffer)
   "Return a childframe displaying BUFFER.