diff --git a/source/blender/blenkernel/intern/object.c b/source/blender/blenkernel/intern/object.c
index 8ac067c0316..7aa23dc6c2b 100644
--- a/source/blender/blenkernel/intern/object.c
+++ b/source/blender/blenkernel/intern/object.c
@@ -678,9 +678,10 @@ void BKE_object_unlink(Object *ob)
 					SpaceOops *so = (SpaceOops *)sl;
 
 					if (so->treestore) {
-						TreeStoreElem *tselem = so->treestore->data;
-						int i;
-						for (i = 0; i < so->treestore->usedelem; i++, tselem++) {
+						TreeStoreElem *tselem;
+						BLI_mempool_iter iter;
+						BLI_mempool_iternew(so->treestore, &iter);
+						while ((tselem = BLI_mempool_iterstep(&iter))) {
 							if (tselem->id == (ID *)ob) tselem->id = NULL;
 						}
 					}
diff --git a/source/blender/blenlib/intern/BLI_mempool.c b/source/blender/blenlib/intern/BLI_mempool.c
index 217a4b9d266..f370f32c31d 100644
--- a/source/blender/blenlib/intern/BLI_mempool.c
+++ b/source/blender/blenlib/intern/BLI_mempool.c
@@ -354,8 +354,18 @@ void BLI_mempool_as_array(BLI_mempool *pool, void **data)
  */
 void *BLI_mempool_as_arrayN(BLI_mempool *pool, const char *allocstr)
 {
-	void *data = MEM_mallocN((size_t)(BLI_mempool_count(pool) * pool->esize), allocstr);
-	BLI_mempool_as_array(pool, data);
+	char *data = MEM_mallocN((size_t)(pool->totused * pool->esize), allocstr);
+	BLI_assert(pool->flag & BLI_MEMPOOL_ALLOW_ITER);
+	if (data) {
+		BLI_mempool_iter iter;
+		char *elem, *p = data;
+		BLI_mempool_iternew(pool, &iter);
+		for (elem = BLI_mempool_iterstep(&iter); elem; elem = BLI_mempool_iterstep(&iter)) {
+			memcpy(p, elem, (size_t)pool->esize);
+			p += pool->esize;
+		}
+		BLI_assert((p - data) == pool->totused * pool->esize);
+	}
 	return data;
 }
 
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 0ff3392ad00..72b426a155a 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -108,6 +108,7 @@
 #include "BLI_math.h"
 #include "BLI_edgehash.h"
 #include "BLI_threads.h"
+#include "BLI_mempool.h"
 
 #include "BLF_translation.h"
 
@@ -5684,16 +5685,24 @@ static void lib_link_screen(FileData *fd, Main *main)
 					}
 					else if (sl->spacetype == SPACE_OUTLINER) {
 						SpaceOops *so= (SpaceOops *)sl;
-						TreeStoreElem *tselem;
-						int a;
-						
 						so->search_tse.id = newlibadr(fd, NULL, so->search_tse.id);
 						
 						if (so->treestore) {
-							tselem = so->treestore->data;
-							for (a=0; a < so->treestore->usedelem; a++, tselem++) {
+							TreeStoreElem *tselem;
+							BLI_mempool_iter iter;
+
+							BLI_mempool_iternew(so->treestore, &iter);
+							while ((tselem = BLI_mempool_iterstep(&iter))) {
 								tselem->id = newlibadr(fd, NULL, tselem->id);
 							}
+							if (so->treehash) {
+								/* update hash table, because it depends on ids too */
+								BLI_ghash_clear(so->treehash, NULL, NULL);
+								BLI_mempool_iternew(so->treestore, &iter);
+								while ((tselem = BLI_mempool_iterstep(&iter))) {
+									BLI_ghash_insert(so->treehash, tselem, tselem);
+								}
+							}
 						}
 					}
 					else if (sl->spacetype == SPACE_NODE) {
@@ -6016,16 +6025,25 @@ void blo_lib_link_screen_restore(Main *newmain, bScreen *curscreen, Scene *cursc
 				}
 				else if (sl->spacetype == SPACE_OUTLINER) {
 					SpaceOops *so= (SpaceOops *)sl;
-					int a;
 					
 					so->search_tse.id = restore_pointer_by_name(newmain, so->search_tse.id, 0);
 					
 					if (so->treestore) {
-						TreeStore *ts = so->treestore;
-						TreeStoreElem *tselem = ts->data;
-						for (a = 0; a < ts->usedelem; a++, tselem++) {
+						TreeStoreElem *tselem;
+						BLI_mempool_iter iter;
+
+						BLI_mempool_iternew(so->treestore, &iter);
+						while ((tselem = BLI_mempool_iterstep(&iter))) {
 							tselem->id = restore_pointer_by_name(newmain, tselem->id, 0);
 						}
+						if (so->treehash) {
+							/* update hash table, because it depends on ids too */
+							BLI_ghash_clear(so->treehash, NULL, NULL);
+							BLI_mempool_iternew(so->treestore, &iter);
+							while ((tselem = BLI_mempool_iterstep(&iter))) {
+								BLI_ghash_insert(so->treehash, tselem, tselem);
+							}
+						}
 					}
 				}
 				else if (sl->spacetype == SPACE_NODE) {
@@ -6283,13 +6301,27 @@ static bool direct_link_screen(FileData *fd, bScreen *sc)
 			else if (sl->spacetype == SPACE_OUTLINER) {
 				SpaceOops *soops = (SpaceOops *) sl;
 				
-				soops->treestore = newdataadr(fd, soops->treestore);
-				if (soops->treestore) {
-					soops->treestore->data = newdataadr(fd, soops->treestore->data);
+				TreeStore *ts = newdataadr(fd, soops->treestore);
+				soops->treestore = NULL;
+				if (ts) {
+					TreeStoreElem *elems = newdataadr(fd, ts->data);
+					
+					soops->treestore = BLI_mempool_create(sizeof(TreeStoreElem), ts->usedelem,
+					                                      512, BLI_MEMPOOL_ALLOW_ITER);
+					if (ts->usedelem && elems) {
+						int i;
+						for (i = 0; i < ts->usedelem; i++) {
+							TreeStoreElem *new_elem = BLI_mempool_alloc(soops->treestore);
+							*new_elem = elems[i];
+						}
+						MEM_freeN(elems);
+					}
 					/* we only saved what was used */
-					soops->treestore->totelem = soops->treestore->usedelem;
 					soops->storeflag |= SO_TREESTORE_CLEANUP;	// at first draw
+					
+					MEM_freeN(ts);
 				}
+				soops->treehash = NULL;
 				soops->tree.first = soops->tree.last= NULL;
 			}
 			else if (sl->spacetype == SPACE_IMAGE) {
diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index e170107713c..12804e8042d 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -144,12 +144,13 @@
 #include "BLI_bitmap.h"
 #include "BLI_blenlib.h"
 #include "BLI_linklist.h"
-#include "BKE_bpath.h"
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
+#include "BLI_mempool.h"
 
 #include "BKE_action.h"
 #include "BKE_blender.h"
+#include "BKE_bpath.h"
 #include "BKE_curve.h"
 #include "BKE_constraint.h"
 #include "BKE_global.h" // for G
@@ -2393,6 +2394,31 @@ static void write_region(WriteData *wd, ARegion *ar, int spacetype)
 	}
 }
 
+static void write_soops(WriteData *wd, SpaceOops *so)
+{
+	BLI_mempool *ts = so->treestore;
+	
+	if (ts) {
+		int elems = BLI_mempool_count(ts);
+		/* linearize mempool to array */
+		TreeStoreElem *data = elems ? BLI_mempool_as_arrayN(ts, "TreeStoreElem") : NULL;
+		TreeStore ts_flat = {elems, elems, data};
+		
+		/* temporarily replace mempool-treestore by flat-treestore */
+		so->treestore = (BLI_mempool *)&ts_flat;
+		writestruct(wd, DATA, "SpaceOops", 1, so);
+		/* restore old treestore */
+		so->treestore = ts;
+		writestruct(wd, DATA, "TreeStore", 1, &ts_flat);
+		if (data) {
+			writestruct(wd, DATA, "TreeStoreElem", elems, data);
+			MEM_freeN(data);
+		}
+	} else {
+		writestruct(wd, DATA, "SpaceOops", 1, so);
+	}
+}
+
 static void write_screens(WriteData *wd, ListBase *scrbase)
 {
 	bScreen *sc;
@@ -2475,15 +2501,7 @@ static void write_screens(WriteData *wd, ListBase *scrbase)
 				}
 				else if (sl->spacetype==SPACE_OUTLINER) {
 					SpaceOops *so= (SpaceOops *)sl;
-					
-					writestruct(wd, DATA, "SpaceOops", 1, so);
-
-					/* outliner */
-					if (so->treestore) {
-						writestruct(wd, DATA, "TreeStore", 1, so->treestore);
-						if (so->treestore->data)
-							writestruct(wd, DATA, "TreeStoreElem", so->treestore->usedelem, so->treestore->data);
-					}
+					write_soops(wd, so);
 				}
 				else if (sl->spacetype==SPACE_IMAGE) {
 					SpaceImage *sima= (SpaceImage *)sl;
diff --git a/source/blender/editors/space_outliner/outliner_draw.c b/source/blender/editors/space_outliner/outliner_draw.c
index b308bd09026..44d5672e7da 100644
--- a/source/blender/editors/space_outliner/outliner_draw.c
+++ b/source/blender/editors/space_outliner/outliner_draw.c
@@ -40,6 +40,7 @@
 #include "BLI_blenlib.h"
 #include "BLI_utildefines.h"
 #include "BLI_ghash.h"
+#include "BLI_mempool.h"
 
 #include "BLF_translation.h"
 
@@ -407,7 +408,7 @@ static void namebutton_cb(bContext *C, void *tsep, char *oldname)
 	SpaceOops *soops = CTX_wm_space_outliner(C);
 	Scene *scene = CTX_data_scene(C);
 	Object *obedit = CTX_data_edit_object(C);
-	TreeStore *ts = soops->treestore;
+	BLI_mempool *ts = soops->treestore;
 	TreeStoreElem *tselem = tsep;
 	
 	if (ts && tselem) {
diff --git a/source/blender/editors/space_outliner/outliner_edit.c b/source/blender/editors/space_outliner/outliner_edit.c
index cef5fe53407..a014724af4a 100644
--- a/source/blender/editors/space_outliner/outliner_edit.c
+++ b/source/blender/editors/space_outliner/outliner_edit.c
@@ -984,7 +984,7 @@ static int ed_operator_outliner_datablocks_active(bContext *C)
  * NOTE: the caller must zero-out all values of the pointers that it passes here first, as
  * this function does not do that yet 
  */
-static void tree_element_to_path(SpaceOops *soops, TreeElement *te, TreeStoreElem *tselem, 
+static void tree_element_to_path(TreeElement *te, TreeStoreElem *tselem,
                                  ID **id, char **path, int *array_index, short *flag, short *UNUSED(groupmode))
 {
 	ListBase hierarchy = {NULL, NULL};
@@ -1152,7 +1152,7 @@ static void do_outliner_drivers_editop(SpaceOops *soops, ListBase *tree, ReportL
 			    RNA_property_animateable(&te->rnaptr, te->directdata))
 			{
 				/* get id + path + index info from the selected element */
-				tree_element_to_path(soops, te, tselem, 
+				tree_element_to_path(te, tselem,
 				                     &id, &path, &array_index, &flag, &groupmode);
 			}
 			
@@ -1333,7 +1333,7 @@ static void do_outliner_keyingset_editop(SpaceOops *soops, KeyingSet *ks, ListBa
 			    RNA_property_animateable(&te->rnaptr, te->directdata))
 			{
 				/* get id + path + index info from the selected element */
-				tree_element_to_path(soops, te, tselem, 
+				tree_element_to_path(te, tselem,
 				                     &id, &path, &array_index, &flag, &groupmode);
 			}
 			
diff --git a/source/blender/editors/space_outliner/outliner_intern.h b/source/blender/editors/space_outliner/outliner_intern.h
index 2310ca9b4b5..5aaf8b5430b 100644
--- a/source/blender/editors/space_outliner/outliner_intern.h
+++ b/source/blender/editors/space_outliner/outliner_intern.h
@@ -48,15 +48,15 @@ struct Object;
 typedef struct TreeElement {
 	struct TreeElement *next, *prev, *parent;
 	ListBase subtree;
-	int xs, ys;         // do selection
-	int store_index;    // offset in tree store
-	short flag;         // flag for non-saved stuff
-	short index;        // index for data arrays
-	short idcode;       // from TreeStore id
-	short xend;         // width of item display, for select
+	int xs, ys;                // do selection
+	TreeStoreElem *store_elem; // element in tree store
+	short flag;                // flag for non-saved stuff
+	short index;               // index for data arrays
+	short idcode;              // from TreeStore id
+	short xend;                // width of item display, for select
 	const char *name;
-	void *directdata;   // Armature Bones, Base, Sequence, Strip...
-	PointerRNA rnaptr;  // RNA Pointer
+	void *directdata;          // Armature Bones, Base, Sequence, Strip...
+	PointerRNA rnaptr;         // RNA Pointer
 }  TreeElement;
 
 /* TreeElement->flag */
@@ -111,7 +111,7 @@ typedef struct TreeElement {
 /* get TreeStoreElem associated with a TreeElement 
  * < a: (TreeElement) tree element to find stored element for
  */
-#define TREESTORE(a) (soops->treestore->data + (a)->store_index)
+#define TREESTORE(a) ((a)->store_elem)
 
 /* size constants */
 #define OL_Y_OFFSET 2
@@ -150,6 +150,7 @@ typedef struct TreeElement {
 
 /* outliner_tree.c ----------------------------------------------- */
 
+void outliner_rebuild_treehash(struct SpaceOops *soops);
 void outliner_free_tree(ListBase *lb);
 void outliner_cleanup_tree(struct SpaceOops *soops);
 
diff --git a/source/blender/editors/space_outliner/outliner_select.c b/source/blender/editors/space_outliner/outliner_select.c
index 9720d981e85..41ad75bb14f 100644
--- a/source/blender/editors/space_outliner/outliner_select.c
+++ b/source/blender/editors/space_outliner/outliner_select.c
@@ -282,7 +282,7 @@ static int tree_element_active_material(bContext *C, Scene *scene, SpaceOops *so
 	return 0;
 }
 
-static int tree_element_active_texture(bContext *C, Scene *scene, SpaceOops *soops, TreeElement *te, int set)
+static int tree_element_active_texture(bContext *C, Scene *scene, SpaceOops *UNUSED(soops), TreeElement *te, int set)
 {
 	TreeElement *tep;
 	TreeStoreElem /* *tselem,*/ *tselemp;
@@ -384,7 +384,7 @@ static int tree_element_active_camera(bContext *UNUSED(C), Scene *scene, SpaceOo
 	return scene->camera == ob;
 }
 
-static int tree_element_active_world(bContext *C, Scene *scene, SpaceOops *soops, TreeElement *te, int set)
+static int tree_element_active_world(bContext *C, Scene *scene, SpaceOops *UNUSED(soops), TreeElement *te, int set)
 {
 	TreeElement *tep;
 	TreeStoreElem *tselem = NULL;
diff --git a/source/blender/editors/space_outliner/outliner_tools.c b/source/blender/editors/space_outliner/outliner_tools.c
index 1e4af4304f0..c1950e62817 100644
--- a/source/blender/editors/space_outliner/outliner_tools.c
+++ b/source/blender/editors/space_outliner/outliner_tools.c
@@ -45,6 +45,7 @@
 
 #include "BLI_blenlib.h"
 #include "BLI_utildefines.h"
+#include "BLI_ghash.h"
 
 #include "BKE_animsys.h"
 #include "BKE_context.h"
@@ -298,13 +299,17 @@ static void object_delete_cb(bContext *C, Scene *scene, TreeElement *te,
 	if (base == NULL)
 		base = BKE_scene_base_find(scene, (Object *)tselem->id);
 	if (base) {
+		SpaceOops *soops = CTX_wm_space_outliner(C);
+
 		// check also library later
 		if (scene->obedit == base->object)
 			ED_object_editmode_exit(C, EM_FREEDATA | EM_FREEUNDO | EM_WAITCURSOR | EM_DO_UNDO);
 		
 		ED_base_object_free_and_unlink(CTX_data_main(C), scene, base);
 		te->directdata = NULL;
+		BLI_ghash_remove(soops->treehash, tselem, NULL, NULL);
 		tselem->id = NULL;
+		BLI_ghash_insert(soops->treehash, tselem, tselem);
 	}
 }
 
diff --git a/source/blender/editors/space_outliner/outliner_tree.c b/source/blender/editors/space_outliner/outliner_tree.c
index 17734f00997..2295af93166 100644
--- a/source/blender/editors/space_outliner/outliner_tree.c
+++ b/source/blender/editors/space_outliner/outliner_tree.c
@@ -63,6 +63,8 @@
 #include "BLI_blenlib.h"
 #include "BLI_utildefines.h"
 #include "BLI_math.h"
+#include "BLI_ghash.h"
+#include "BLI_mempool.h"
 
 #include "BLF_translation.h"
 
@@ -93,105 +95,127 @@
 
 static void outliner_storage_cleanup(SpaceOops *soops)
 {
-	TreeStore *ts = soops->treestore;
+	BLI_mempool *ts = soops->treestore;
 	
 	if (ts) {
 		TreeStoreElem *tselem;
-		int a, unused = 0;
+		int unused = 0;
 		
 		/* each element used once, for ID blocks with more users to have each a treestore */
-		for (a = 0, tselem = ts->data; a < ts->usedelem; a++, tselem++) tselem->used = 0;
+		BLI_mempool_iter iter;
+
+		BLI_mempool_iternew(ts, &iter);
+		while ((tselem = BLI_mempool_iterstep(&iter))) {
+			tselem->used = 0;
+		}
 		
 		/* cleanup only after reading file or undo step, and always for
 		 * RNA datablocks view in order to save memory */
 		if (soops->storeflag & SO_TREESTORE_CLEANUP) {
-			
-			for (a = 0, tselem = ts->data; a < ts->usedelem; a++, tselem++) {
+			BLI_mempool_iternew(ts, &iter);
+			while ((tselem = BLI_mempool_iterstep(&iter))) {
 				if (tselem->id == NULL) unused++;
 			}
 			
 			if (unused) {
-				if (ts->usedelem == unused) {
-					MEM_freeN(ts->data);
-					ts->data = NULL;
-					ts->usedelem = ts->totelem = 0;
+				if (BLI_mempool_count(ts) == unused) {
+					BLI_mempool_destroy(ts);
+					soops->treestore = NULL;
+
+					if (soops->treehash) {
+						BLI_ghash_free(soops->treehash, NULL, NULL);
+						soops->treehash = NULL;
+					}
 				}
 				else {
-					TreeStoreElem *tsnewar, *tsnew;
-					
-					tsnew = tsnewar = MEM_mallocN((ts->usedelem - unused) * sizeof(TreeStoreElem), "new tselem");
-					for (a = 0, tselem = ts->data; a < ts->usedelem; a++, tselem++) {
+					TreeStoreElem *tsenew;
+					BLI_mempool *new_ts = BLI_mempool_create(sizeof(TreeStoreElem), BLI_mempool_count(ts) - unused,
+					                                         512, BLI_MEMPOOL_ALLOW_ITER);
+					BLI_mempool_iternew(ts, &iter);
+					while ((tselem = BLI_mempool_iterstep(&iter))) {
 						if (tselem->id) {
-							*tsnew = *tselem;
-							tsnew++;
+							tsenew = BLI_mempool_alloc(new_ts);
+							*tsenew = *tselem;
+						}
+					}
+					BLI_mempool_destroy(ts);
+					soops->treestore = new_ts;
+
+					if (soops->treehash) {
+						/* update hash table to fix broken pointers */
+						BLI_ghash_clear(soops->treehash, NULL, NULL);
+						BLI_mempool_iternew(soops->treestore, &iter);
+						while ((tselem = BLI_mempool_iterstep(&iter))) {
+							BLI_ghash_insert(soops->treehash, tselem, tselem);
 						}
 					}
-					MEM_freeN(ts->data);
-					ts->data = tsnewar;
-					ts->usedelem -= unused;
-					ts->totelem = ts->usedelem;
 				}
 			}
 		}
 	}
 }
 
-/* XXX - THIS FUNCTION IS INCREDIBLY SLOW
- * ... it can bring blenders tools and viewport to a grinding halt because of searching
- * for duplicate items every times they are added.
- *
- * TODO (possible speedups)
- * - use a hash for duplicate (could even store a hash per type)
- * - use mempool for TreeElements
- * */
+static unsigned int tse_hash(const void *ptr)
+{
+	const TreeStoreElem *tse = (const TreeStoreElem *)ptr;
+	unsigned int hash;
+	BLI_assert(tse->type || !tse->nr);
+	hash = BLI_ghashutil_inthash(SET_INT_IN_POINTER((tse->nr << 16) + tse->type));
+	hash ^= BLI_ghashutil_inthash(tse->id);
+	return hash;
+}
+
+static int tse_cmp(const void *a, const void *b)
+{
+	const TreeStoreElem *tse_a = (const TreeStoreElem *)a;
+	const TreeStoreElem *tse_b = (const TreeStoreElem *)b;
+	return tse_a->type != tse_b->type || tse_a->nr != tse_b->nr || tse_a->id != tse_b->id;
+}
+
 static void check_persistent(SpaceOops *soops, TreeElement *te, ID *id, short type, short nr)
 {
-	TreeStore *ts;
-	TreeStoreElem *tselem;
-	int a;
+	/* When treestore comes directly from readfile.c, treehash is empty;
+	 * In this case we don't want to get TSE_CLOSED while adding elements one by one,
+     * that is why this function restores treehash */
+	bool restore_treehash = (soops->treestore && !soops->treehash);
+	TreeStoreElem *tselem, elem_template;
 	
-	/* case 1; no TreeStore */
 	if (soops->treestore == NULL) {
-		soops->treestore = MEM_callocN(sizeof(TreeStore), "treestore");
+		/* if treestore was not created in readfile.c, create it here */
+		soops->treestore = BLI_mempool_create(sizeof(TreeStoreElem), 1, 512, BLI_MEMPOOL_ALLOW_ITER);
+	}
+	if (soops->treehash == NULL) {
+		soops->treehash = BLI_ghash_new(tse_hash, tse_cmp, "treehash");
 	}
-	ts = soops->treestore;
 	
+	if (restore_treehash) {
+		BLI_mempool_iter iter;
+		BLI_mempool_iternew(soops->treestore, &iter);
+		while ((tselem = BLI_mempool_iterstep(&iter))) {
+			BLI_ghash_insert(soops->treehash, tselem, tselem);
+		}
+	}
+
 	/* check if 'te' is in treestore */
-	tselem = ts->data;
-	for (a = 0; a < ts->usedelem; a++, tselem++) {
-		if ((tselem->used == 0) && (tselem->type == type) && (tselem->id == id)) {
-			if ((type == 0) || (tselem->nr == nr)) {
-				te->store_index = a;
-				tselem->used = 1;
-				return;
-			}
-		}
+	elem_template.type = type;
+	elem_template.nr = type ? nr : 0;  // we're picky! :)
+	elem_template.id = id;
+	tselem = BLI_ghash_lookup(soops->treehash, &elem_template);
+	if (tselem && !tselem->used) {
+		te->store_elem = tselem;
+		tselem->used = 1;
+		return;
 	}
-	
+
 	/* add 1 element to treestore */
-	if (ts->usedelem == ts->totelem) {
-		TreeStoreElem *tsnew;
-		
-		tsnew = MEM_mallocN((ts->totelem + TS_CHUNK) * sizeof(TreeStoreElem), "treestore data");
-		if (ts->data) {
-			memcpy(tsnew, ts->data, ts->totelem * sizeof(TreeStoreElem));
-			MEM_freeN(ts->data);
-		}
-		ts->data = tsnew;
-		ts->totelem += TS_CHUNK;
-	}
-	
-	tselem = ts->data + ts->usedelem;
-	
+	tselem = BLI_mempool_alloc(soops->treestore);
 	tselem->type = type;
-	if (type) tselem->nr = nr;  // we're picky! :)
-	else tselem->nr = 0;
+	tselem->nr = type ? nr : 0;
 	tselem->id = id;
 	tselem->used = 0;
 	tselem->flag = TSE_CLOSED;
-	te->store_index = ts->usedelem;
-	
-	ts->usedelem++;
+	te->store_elem = tselem;
+	BLI_ghash_insert(soops->treehash, tselem, tselem);
 }
 
 /* ********************************************************* */
@@ -216,15 +240,14 @@ void outliner_cleanup_tree(SpaceOops *soops)
 	outliner_storage_cleanup(soops);
 }
 
-/* Find ith item from the treestore */
-static TreeElement *outliner_find_tree_element(ListBase *lb, int store_index)
+/* Find specific item from the treestore */
+static TreeElement *outliner_find_tree_element(ListBase *lb, TreeStoreElem *store_elem)
 {
-	TreeElement *te = lb->first, *tes;
-	while (te) {
-		if (te->store_index == store_index) return te;
-		tes = outliner_find_tree_element(&te->subtree, store_index);
+	TreeElement *te, *tes;
+	for (te = lb->first; te; te = te->next) {
+		if (te->store_elem == store_elem) return te;
+		tes = outliner_find_tree_element(&te->subtree, store_elem);
 		if (tes) return tes;
-		te = te->next;
 	}
 	return NULL;
 }
@@ -232,23 +255,18 @@ static TreeElement *outliner_find_tree_element(ListBase *lb, int store_index)
 /* tse is not in the treestore, we use its contents to find a match */
 TreeElement *outliner_find_tse(SpaceOops *soops, TreeStoreElem *tse)
 {
-	TreeStore *ts = soops->treestore;
-	TreeStoreElem *tselem;
-	int a;
-	
+	GHash *th = soops->treehash;
+	TreeStoreElem *tselem, tselem_template;
+
 	if (tse->id == NULL) return NULL;
 	
 	/* check if 'tse' is in treestore */
-	tselem = ts->data;
-	for (a = 0; a < ts->usedelem; a++, tselem++) {
-		if ((tse->type == 0 && tselem->type == 0) || (tselem->type == tse->type && tselem->nr == tse->nr)) {
-			if (tselem->id == tse->id) {
-				break;
-			}
-		}
-	}
+	tselem_template.id = tse->id;
+	tselem_template.type = tse->type;
+	tselem_template.nr = tse->type ? tse->nr : 0;
+	tselem = BLI_ghash_lookup(th, &tselem_template);
 	if (tselem) 
-		return outliner_find_tree_element(&soops->tree, a);
+		return outliner_find_tree_element(&soops->tree, tselem);
 	
 	return NULL;
 }
@@ -274,7 +292,7 @@ TreeElement *outliner_find_id(SpaceOops *soops, ListBase *lb, ID *id)
 }
 
 
-ID *outliner_search_back(SpaceOops *soops, TreeElement *te, short idcode)
+ID *outliner_search_back(SpaceOops *UNUSED(soops), TreeElement *te, short idcode)
 {
 	TreeStoreElem *tselem;
 	te = te->parent;
@@ -1187,7 +1205,7 @@ static void outliner_add_seq_dup(SpaceOops *soops, Sequence *seq, TreeElement *t
 /* Hierarchy --------------------------------------------- */
 
 /* make sure elements are correctly nested */
-static void outliner_make_hierarchy(SpaceOops *soops, ListBase *lb)
+static void outliner_make_hierarchy(ListBase *lb)
 {
 	TreeElement *te, *ten, *tep;
 	TreeStoreElem *tselem;
@@ -1489,7 +1507,7 @@ void outliner_build_tree(Main *mainvar, Scene *scene, SpaceOops *soops)
 	Object *ob;
 	TreeElement *te = NULL, *ten;
 	TreeStoreElem *tselem;
-	int show_opened = (soops->treestore == NULL); /* on first view, we open scenes */
+	int show_opened = !soops->treestore || !BLI_mempool_count(soops->treestore); /* on first view, we open scenes */
 
 	/* Are we looking for something - we want to tag parents to filter child matches
 	 * - NOT in datablocks view - searching all datablocks takes way too long to be useful
@@ -1561,7 +1579,7 @@ void outliner_build_tree(Main *mainvar, Scene *scene, SpaceOops *soops)
 				ten = outliner_add_element(soops, &te->subtree, base->object, te, 0, 0);
 				ten->directdata = base;
 			}
-			outliner_make_hierarchy(soops, &te->subtree);
+			outliner_make_hierarchy(&te->subtree);
 			/* clear id.newid, to prevent objects be inserted in wrong scenes (parent in other scene) */
 			for (base = sce->base.first; base; base = base->next) base->object->id.newid = NULL;
 		}
@@ -1574,14 +1592,14 @@ void outliner_build_tree(Main *mainvar, Scene *scene, SpaceOops *soops)
 			ten = outliner_add_element(soops, &soops->tree, base->object, NULL, 0, 0);
 			ten->directdata = base;
 		}
-		outliner_make_hierarchy(soops, &soops->tree);
+		outliner_make_hierarchy(&soops->tree);
 	}
 	else if (soops->outlinevis == SO_VISIBLE) {
 		for (base = scene->base.first; base; base = base->next) {
 			if (base->lay & scene->lay)
 				outliner_add_element(soops, &soops->tree, base->object, NULL, 0, 0);
 		}
-		outliner_make_hierarchy(soops, &soops->tree);
+		outliner_make_hierarchy(&soops->tree);
 	}
 	else if (soops->outlinevis == SO_GROUPS) {
 		Group *group;
@@ -1595,7 +1613,7 @@ void outliner_build_tree(Main *mainvar, Scene *scene, SpaceOops *soops)
 					ten = outliner_add_element(soops, &te->subtree, go->ob, te, 0, 0);
 					ten->directdata = NULL; /* eh, why? */
 				}
-				outliner_make_hierarchy(soops, &te->subtree);
+				outliner_make_hierarchy(&te->subtree);
 				/* clear id.newid, to prevent objects be inserted in wrong scenes (parent in other scene) */
 				for (go = group->gobject.first; go; go = go->next) go->ob->id.newid = NULL;
 			}
@@ -1610,7 +1628,7 @@ void outliner_build_tree(Main *mainvar, Scene *scene, SpaceOops *soops)
 					ten->directdata = base;
 				}
 			}
-			outliner_make_hierarchy(soops, &soops->tree);
+			outliner_make_hierarchy(&soops->tree);
 		}
 	}
 	else if (soops->outlinevis == SO_SELECTED) {
@@ -1622,7 +1640,7 @@ void outliner_build_tree(Main *mainvar, Scene *scene, SpaceOops *soops)
 				}
 			}
 		}
-		outliner_make_hierarchy(soops, &soops->tree);
+		outliner_make_hierarchy(&soops->tree);
 	}
 	else if (soops->outlinevis == SO_SEQUENCE) {
 		Sequence *seq;
diff --git a/source/blender/editors/space_outliner/space_outliner.c b/source/blender/editors/space_outliner/space_outliner.c
index 8da244b1db1..9c51265f917 100644
--- a/source/blender/editors/space_outliner/space_outliner.c
+++ b/source/blender/editors/space_outliner/space_outliner.c
@@ -37,6 +37,8 @@
 #include "BLI_blenlib.h"
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
+#include "BLI_mempool.h"
+#include "BLI_ghash.h"
 
 #include "BKE_context.h"
 #include "BKE_screen.h"
@@ -426,10 +428,11 @@ static void outliner_free(SpaceLink *sl)
 	
 	outliner_free_tree(&soutliner->tree);
 	if (soutliner->treestore) {
-		if (soutliner->treestore->data) MEM_freeN(soutliner->treestore->data);
-		MEM_freeN(soutliner->treestore);
+		BLI_mempool_destroy(soutliner->treestore);
+	}
+	if (soutliner->treehash) {
+		BLI_ghash_free(soutliner->treehash, NULL, NULL);
 	}
-	
 }
 
 /* spacetype; init callback */
diff --git a/source/blender/makesdna/DNA_outliner_types.h b/source/blender/makesdna/DNA_outliner_types.h
index 5f9c90f09f7..53061b55e2d 100644
--- a/source/blender/makesdna/DNA_outliner_types.h
+++ b/source/blender/makesdna/DNA_outliner_types.h
@@ -32,6 +32,8 @@
 #ifndef __DNA_OUTLINER_TYPES_H__
 #define __DNA_OUTLINER_TYPES_H__
 
+#include "DNA_defs.h"
+
 struct ID;
 
 typedef struct TreeStoreElem {
@@ -39,9 +41,12 @@ typedef struct TreeStoreElem {
 	struct ID *id;
 } TreeStoreElem;
 
+/* used only to store data in in blend files */
 typedef struct TreeStore {
-	int totelem, usedelem;
-	TreeStoreElem *data;
+	int totelem  DNA_DEPRECATED; /* was previously used for memory preallocation */
+	int usedelem;                /* number of elements in data array */
+	TreeStoreElem *data;         /* elements to be packed from mempool in writefile.c
+	                              * or extracted to mempool in readfile.c */
 } TreeStore;
 
 /* TreeStoreElem->flag */
diff --git a/source/blender/makesdna/DNA_space_types.h b/source/blender/makesdna/DNA_space_types.h
index 2d87cb1d890..c562a1fefae 100644
--- a/source/blender/makesdna/DNA_space_types.h
+++ b/source/blender/makesdna/DNA_space_types.h
@@ -72,6 +72,8 @@ struct wmTimer;
 struct MovieClip;
 struct MovieClipScopes;
 struct Mask;
+struct GHash;
+struct BLI_mempool;
 
 
 /* SpaceLink (Base) ==================================== */
@@ -244,13 +246,14 @@ typedef struct SpaceOops {
 	View2D v2d DNA_DEPRECATED;  /* deprecated, copied to region */
 	
 	ListBase tree;
-	struct TreeStore *treestore;
+	struct BLI_mempool *treestore;
 	
 	/* search stuff */
 	char search_string[32];
 	struct TreeStoreElem search_tse;
 
 	short flag, outlinevis, storeflag, search_flags;
+	struct GHash *treehash;
 } SpaceOops;