diff --git a/libgst/interp-bc.inl b/libgst/interp-bc.inl
index 8819481..25b756a 100644
--- a/libgst/interp-bc.inl
+++ b/libgst/interp-bc.inl
@@ -173,6 +173,7 @@
 } while(0)
 
 
+
 void
 _gst_send_message_internal (OOP sendSelector, 
 			    int sendArgs, 
@@ -192,6 +193,7 @@ _gst_send_message_internal (OOP sendSelector,
      zeros.  */
 
   _gst_sample_counter++;
+
   hashIndex = METHOD_CACHE_HASH (sendSelector, method_class);
   methodData = &method_cache[hashIndex];
 
diff --git a/libgst/oop.c b/libgst/oop.c
index 2e8b7fd..5ab82df 100644
--- a/libgst/oop.c
+++ b/libgst/oop.c
@@ -66,6 +66,7 @@
 
 /* Define this flag to turn on debugging code for OOP table management */
 /* #define GC_DEBUGGING */
+#define GC_DEBUGGING
 
 /* Define this flag to disable incremental garbage collection */
 /* #define NO_INCREMENTAL_GC */
@@ -353,6 +354,9 @@ _gst_init_mem (size_t eden, size_t survivor, size_t old,
       _gst_inc_init_registry ();
     }
 
+  _gst_mem.markQueue = xcalloc (128 * K, sizeof (*_gst_mem.markQueue));
+  _gst_mem.currentMarkQueue = &_gst_mem.markQueue[0];
+  _gst_mem.lastMarkQueue = &_gst_mem.markQueue[128 * K];
 }
 
 void _gst_update_object_memory_oop (OOP oop)
@@ -2207,7 +2211,6 @@ mark_ephemeron_oops (void)
 }
 
 #define TAIL_MARK_OOP(newOOP) do { \
-  PREFETCH_ADDR ((newOOP)->object, PREF_READ | PREF_NTA); \
   oop = (newOOP); \
   goto markOne;		/* tail recurse!!! */ \
 } while(0)
@@ -2223,52 +2226,40 @@ mark_ephemeron_oops (void)
 void
 _gst_mark_an_oop_internal (OOP oop)
 {
-  OOP *curOOP, *atEndOOP;
-  goto markOne;
+ OOP *curOOP, *atEndOOP;
+
+ goto markOne;
 
  markRange:
-  {			/* in the loop! */
-#if defined (GC_DEBUGGING)
-    gst_object obj = (gst_object) (curOOP - 1);	/* for debugging */
-#endif
-    for (;;)
+  {
+    while (curOOP < atEndOOP)
       {
-        /* in a loop, do next iteration */
         oop = *curOOP;
-        PREFETCH_LOOP (curOOP, PREF_READ | PREF_NTA);
-        curOOP++;
-        if (IS_OOP (oop))
+
+        if (!IS_OOP (oop) || IS_OOP_MARKED (oop))
           {
-#if defined (GC_DEBUGGING)
-            if UNCOMMON (!IS_OOP_ADDR (oop))
-              {
-                printf
-                  ("Error! Invalid OOP %p was found inside %p!\n",
-                   oop, obj);
-                abort ();
-              }
-            else
-#endif
-              if (!IS_OOP_MARKED (oop))
-                {
-                  PREFETCH_START (oop->object, PREF_READ | PREF_NTA);
-
-                  /* On the last object in the set, reuse the
-                     current invocation. oop is valid, so we go to
-                     the single-object case */
-                  if UNCOMMON (curOOP == atEndOOP)
-                    goto markOne;
-
-                  _gst_mark_an_oop_internal (oop);
-                  continue;
-                }
+            curOOP++;
+            continue ;
+          }
+
+        if (_gst_mem.currentMarkQueue == _gst_mem.lastMarkQueue)
+          {
+            const size_t size = _gst_mem.lastMarkQueue - _gst_mem.markQueue;
+
+            _gst_mem.markQueue = (OOP *) xrealloc (_gst_mem.markQueue, 10 * size * sizeof (*_gst_mem.markQueue));
+            _gst_mem.currentMarkQueue = &_gst_mem.markQueue[size];
+            _gst_mem.lastMarkQueue = &_gst_mem.markQueue[10 * size];
           }
 
-        /* Place the check here so that the continue above skips it.  */
-        if UNCOMMON (curOOP == atEndOOP)
-          return;
+        oop->flags |= F_REACHABLE;
+        *_gst_mem.currentMarkQueue = oop;
+        _gst_mem.currentMarkQueue++;
+
+        curOOP++;
       }
-  }
+
+      goto loop;
+    }
 
  markOne:
   {
@@ -2329,10 +2320,18 @@ _gst_mark_an_oop_internal (OOP oop)
           TAIL_MARK_OOP (objClass);
       }
   }
+
+  loop:
+  if (_gst_mem.currentMarkQueue > _gst_mem.markQueue)
+    {
+      _gst_mem.currentMarkQueue--;
+      oop = *_gst_mem.currentMarkQueue;
+      goto markOne;
+    }
 }
 
-void
-_gst_mark_oop_range (OOP *curOOP, OOP *atEndOOP)
+ void
+ _gst_mark_oop_range (OOP *curOOP, OOP *atEndOOP)
 {
   OOP *pOOP;
   for (pOOP = curOOP; pOOP < atEndOOP; pOOP++)
diff --git a/libgst/oop.h b/libgst/oop.h
index 6816b3f..8d1c274 100644
--- a/libgst/oop.h
+++ b/libgst/oop.h
@@ -193,6 +193,9 @@ struct memory_space
   struct new_space eden;
   struct surv_space surv[2], tenuring_queue;
 
+  OOP *markQueue;
+  OOP *currentMarkQueue, *lastMarkQueue;
+
   /* The current state of the copying collector's scan phase.  */
   struct cheney_scan_state scan;
 
@@ -380,10 +383,6 @@ extern void _gst_grey_oop_range (PTR from,
 			         size_t size) 
   ATTRIBUTE_HIDDEN;
 
-/* Mark OOP and the pointers pointed by that.  */
-extern void _gst_mark_an_oop_internal (OOP oop)
-  ATTRIBUTE_HIDDEN;
-
 /* Fully initialize the builtin objects, possible after the respective
    classes have been created.  */
 extern void _gst_init_builtin_objects_classes (void) 
diff --git a/libgst/oop.inl b/libgst/oop.inl
index 279dd1b..f2abd7e 100644
--- a/libgst/oop.inl
+++ b/libgst/oop.inl
@@ -62,10 +62,10 @@ static inline OOP alloc_oop (PTR obj, intptr_t flags);
 
 /* Mark the OOP object because it is part of the root set.  Integers
    and already-marked OOPs are not processed silently.  */
-#define MAYBE_MARK_OOP(oop) do {			  \
-  if (IS_OOP(oop) && !IS_OOP_MARKED(oop)) {		  \
-    _gst_mark_an_oop_internal((oop));			  \
-  }							  \
+#define MAYBE_MARK_OOP(oop) do {		  \
+  if (IS_OOP(oop) && !IS_OOP_MARKED(oop)) {	  \
+    _gst_mark_an_oop_internal (oop); 	  	  \
+  }						  \
 } while(0)
 
 #define IS_OOP_COPIED(oop) \