* lisp/jit-lock.el (jit-lock-function): Don't defer if jit-lock-defer-time

is 0 and there is no input pending.

lisp/ChangeLog

+2014-12-16  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* jit-lock.el (jit-lock-function): Don't defer if jit-lock-defer-time
+	is 0 and there is no input pending.
+
 2014-12-15  Juri Linkov  <juri@linkov.net>
 
 	* replace.el (query-replace-read-from): Use query-replace-compile-replacement

lisp/jit-lock.el

@@ -125,7 +125,8 @@ The value of this variable is used when JIT Lock mode is turned on."
 
 (defcustom jit-lock-defer-time nil ;; 0.25
   "Idle time after which deferred fontification should take place.
-If nil, fontification is not deferred."
+If nil, fontification is not deferred.
+If 0, then fontification is only deferred while there is input pending."
   :group 'jit-lock
   :type '(choice (const :tag "never" nil)
 	         (number :tag "seconds")))
@@ -333,7 +334,9 @@ Only applies to the current buffer."
 This function is added to `fontification-functions' when `jit-lock-mode'
 is active."
   (when (and jit-lock-mode (not memory-full))
-    (if (null jit-lock-defer-timer)
+    (if (not (and jit-lock-defer-timer
+                  (or (not (eq jit-lock-defer-time 0))
+                      (input-pending-p))))
 	;; No deferral.
 	(jit-lock-fontify-now start (+ start jit-lock-chunk-size))
       ;; Record the buffer for later fontification.