(prepare_to_modify_buffer): Don't call verify_overlay_modification if

no overlays, or verify_interval_modification no intervals.

(insert_1): Don't call interval fns if buffer has none.

src/insdel.c

@@ -350,8 +350,11 @@ insert_1 (string, length, inherit)
 
   bcopy (string, GPT_ADDR, length);
 
-  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
-  offset_intervals (current_buffer, PT, length);
+#ifdef USE_TEXT_PROPERTIES
+  if (current_buffer->intervals != 0)
+    /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES.  */
+    offset_intervals (current_buffer, PT, length);
+#endif
 
   GAP_SIZE -= length;
   GPT += length;
@@ -359,9 +362,11 @@ insert_1 (string, length, inherit)
   Z += length;
   adjust_point (length);
 
-  if (!inherit)
+#ifdef USE_TEXT_PROPERTIES
+  if (!inherit && current_buffer->intervals != 0)
     Fset_text_properties (make_number (PT - length), make_number (PT),
 			  Qnil, Qnil);
+#endif
 }
 
 /* Insert the part of the text of STRING, a Lisp object assumed to be
@@ -595,9 +600,12 @@ prepare_to_modify_buffer (start, end)
     Fbarf_if_buffer_read_only ();
 
   /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
-  verify_interval_modification (current_buffer, start, end);
+  if (current_buffer->intervals != 0)
+    verify_interval_modification (current_buffer, start, end);
 
-  verify_overlay_modification (start, end);
+  if (!NILP (current_buffer->overlays_before)
+      || !NILP (current_buffer->overlays_after))
+    verify_overlay_modification (start, end);
 
 #ifdef CLASH_DETECTION
   if (!NILP (current_buffer->filename)