diff --git a/libs/container/container.h b/libs/container/container.h
index 47f823e6..9e8c03f5 100644
--- a/libs/container/container.h
+++ b/libs/container/container.h
@@ -58,6 +58,7 @@ const Type& get() const {
 
 
 /// \brief An adaptor to make std::list into a Unique Sequence - which cannot contain the same value more than once.
+/// It's illegal to modify inserted values directly!
 /// \param Value Uniquely identifies itself. Must provide a copy-constructor and an equality operator.
 template<typename Value>
 class UnsortedSet
@@ -69,6 +70,38 @@ typedef typename Values::iterator iterator;
 typedef typename Values::const_iterator const_iterator;
 typedef typename Values::reverse_iterator reverse_iterator;
 typedef typename Values::const_reverse_iterator const_reverse_iterator;
+private:
+struct Compare{
+	using is_transparent = void;
+
+	bool operator()( const iterator& one, const iterator& other ) const {
+		return *one < *other;
+	}
+	bool operator()( const Value& va, const iterator& it ) const {
+		return va < *it;
+	}
+	bool operator()( const iterator& it, const Value& va ) const {
+		return *it < va;
+	}
+};
+std::set<iterator, Compare> m_set; // store sorted iterators for fast lookup
+void init_set(){ // only load set, when lookup is needed
+	if( m_set.empty() )
+		for( auto it = begin(); it != end(); ++it )
+			m_set.emplace( it );
+}
+public:
+
+UnsortedSet() = default;
+UnsortedSet( const UnsortedSet& other ) : m_values( other.m_values ), m_set(){
+}
+UnsortedSet( UnsortedSet&& ) noexcept = default;
+UnsortedSet& operator=( const UnsortedSet& other ){
+	m_values = other.m_values;
+	m_set.clear();
+	return *this;
+}
+UnsortedSet& operator=( UnsortedSet&& ) noexcept = default;
 
 iterator begin(){
 	return m_values.begin();
@@ -103,23 +136,32 @@ std::size_t size() const {
 }
 void clear(){
 	m_values.clear();
+	m_set.clear();
 }
 
 void swap( UnsortedSet& other ){
 	std::swap( m_values, other.m_values );
+	std::swap( m_set, other.m_set );
 }
+
 iterator insert( const Value& value ){
-	ASSERT_MESSAGE( find( value ) == end(), "UnsortedSet::insert: already added" );
+	init_set();
 	m_values.push_back( value );
+	const bool inserted = m_set.emplace( --end() ).second;
+	ASSERT_MESSAGE( inserted, "UnsortedSet::insert: already added" );
 	return --end();
 }
 void erase( const Value& value ){
-	iterator i = find( value );
-	ASSERT_MESSAGE( i != end(), "UnsortedSet::erase: not found" );
-	m_values.erase( i );
+	init_set();
+	const auto it = m_set.find( value );
+	ASSERT_MESSAGE( it != m_set.end(), "UnsortedSet::erase: not found" );
+	m_values.erase( *it );
+	m_set.erase( it );
 }
 iterator find( const Value& value ){
-	return std::find( begin(), end(), value );
+	init_set();
+	const auto it = m_set.find( value );
+	return it == m_set.end()? m_values.end() : *it;
 }
 };
 
@@ -274,7 +316,7 @@ void erase( const Value& value ){
 	m_values.erase( i );
 }
 iterator find( const Value& value ){
-	return std::find( begin(), end(), value );
+	return m_values.find( value );
 }
 };
 
diff --git a/radiant/treemodel.cpp b/radiant/treemodel.cpp
index 57e6812c..4b1387f9 100644
--- a/radiant/treemodel.cpp
+++ b/radiant/treemodel.cpp
@@ -745,6 +745,10 @@ class GraphTreeNode
 {
 typedef std::map<std::pair<CopiedString, scene::Node*>, GraphTreeNode*> ChildNodes;
 ChildNodes m_childnodes;
+
+std::list<char> m_list; // dummy list for child index identification
+std::list<char>::const_iterator m_parentListIterator; // iterator from parent's list
+bool m_searchFromEnd = false; //silly optimization
 public:
 Reference<scene::Instance> m_instance;
 GraphTreeNode* m_parent;
@@ -761,6 +765,11 @@ GraphTreeNode( scene::Instance& instance ) : m_instance( instance ), m_parent( 0
 	m_instance.get().setChildSelectedChangedCallback( Callback() );
 	ASSERT_MESSAGE( empty(), "GraphTreeNode::~GraphTreeNode: memory leak" );
 }
+GraphTreeNode() = delete;
+GraphTreeNode( const GraphTreeNode& ) = delete;
+GraphTreeNode( GraphTreeNode&& ) noexcept = delete;
+GraphTreeNode& operator=( const GraphTreeNode& ) = delete;
+GraphTreeNode& operator=( GraphTreeNode&& ) noexcept = delete;
 
 iterator begin(){
 	return m_childnodes.begin();
@@ -775,25 +784,30 @@ size_type size() const {
 bool empty() const {
 	return m_childnodes.empty();
 }
+// may not be called on the root node!
+int getIndex() const {
+	const int idx = m_parent->m_searchFromEnd?
+	                m_parent->m_list.size() - std::distance( m_parentListIterator, m_parent->m_list.cend() ) :
+	                std::distance( m_parent->m_list.cbegin(), m_parentListIterator );
+	m_parent->m_searchFromEnd = idx * 2 > int( m_parent->size() );
+	return idx;
+}
 
 iterator insert( const value_type& value ){
 	iterator i = m_childnodes.insert( value ).first;
 	( *i ).second->m_parent = this;
+	const auto pos = std::next( i ) == end()? m_list.end() : std::next( i )->second->m_parentListIterator;
+	i->second->m_parentListIterator = m_list.insert( pos, 'a' );
 	return i;
 }
 void erase( iterator i ){
+	m_list.erase( i->second->m_parentListIterator );
 	m_childnodes.erase( i );
 }
 iterator find( const key_type& key ){
 	return m_childnodes.find( key );
 }
 
-void swap( GraphTreeNode& other ){
-	std::swap( m_parent, other.m_parent );
-	std::swap( m_childnodes, other.m_childnodes );
-	std::swap( m_instance, other.m_instance );
-}
-
 void rowChanged(){
 	graph_tree_model_row_changed( *this );
 }
@@ -884,15 +898,7 @@ static GtkTreePath* graph_tree_model_get_path( GtkTreeModel* tree_model, GtkTree
 
 	for ( GraphTreeNode* node = ( *graph_iterator_read_tree_iter( iter ) ).second; node != graph; node = node->m_parent )
 	{
-		std::size_t index = 0;
-		for ( GraphTreeNode::iterator i = node->m_parent->begin(); i != node->m_parent->end(); ++i, ++index )
-		{
-			if ( ( *i ).second == node ) {
-				gtk_tree_path_prepend_index( path, gint( index ) );
-				break;
-			}
-		}
-		ASSERT_MESSAGE( index != node->m_parent->size(), "error resolving tree path" );
+		gtk_tree_path_prepend_index( path, gint( node->getIndex() ) );
 	}
 
 	return path;