diff --git a/pcbnew/connectivity/connectivity_items.h b/pcbnew/connectivity/connectivity_items.h
index 3e6ca7e9a..e41f84c54 100644
--- a/pcbnew/connectivity/connectivity_items.h
+++ b/pcbnew/connectivity/connectivity_items.h
@@ -109,7 +109,7 @@ public:
         m_cluster = aCluster;
     }
 
-    inline std::shared_ptr<CN_CLUSTER> GetCluster() const
+    inline const std::shared_ptr<CN_CLUSTER>& GetCluster() const
     {
         return m_cluster;
     }
@@ -159,7 +159,7 @@ typedef std::vector<CN_ANCHOR_PTR>  CN_ANCHORS;
 class CN_ITEM : public INTRUSIVE_LIST<CN_ITEM>
 {
 public:
-    using CONNECTED_ITEMS = std::set<CN_ITEM*>;
+    using CONNECTED_ITEMS = std::vector<CN_ITEM*>;
 
 private:
     BOARD_CONNECTED_ITEM* m_parent;
@@ -178,8 +178,8 @@ private:
     ///> valid flag, used to identify garbage items (we use lazy removal)
     bool m_valid;
 
-    ///> mutex protecting this item's connected_items set to allow parallel connection threads
-    std::mutex m_listLock;
+    ///> atomic var protecting this item's connected_items set to allow parallel connection threads
+    std::atomic_flag m_listLock = ATOMIC_FLAG_INIT;
 
 protected:
     ///> dirty flag, used to identify recently added item not yet scanned into the connectivity search
@@ -201,15 +201,16 @@ public:
         m_visited = false;
         m_valid = true;
         m_dirty = true;
-        m_anchors.reserve( 2 );
+        m_anchors.reserve( std::max (6, aAnchorCount) );
         m_layers = LAYER_RANGE( 0, PCB_LAYER_ID_COUNT );
+        m_connected.reserve (8);
     }
 
     virtual ~CN_ITEM() {};
 
     void AddAnchor( const VECTOR2I& aPos )
     {
-        m_anchors.emplace_back( std::make_unique<CN_ANCHOR>( aPos, this ) );
+        m_anchors.emplace_back( std::make_shared<CN_ANCHOR>( aPos, this ) );
     }
 
     CN_ANCHORS& Anchors()
@@ -319,8 +320,14 @@ public:
 
     void Connect( CN_ITEM* b )
     {
-        std::lock_guard<std::mutex> lock( m_listLock );
-        m_connected.insert( b );
+        while (m_listLock.test_and_set ()) { }
+
+        auto i = std::lower_bound (m_connected.begin (), m_connected.end (), b);
+        if (i != m_connected.end () && *i == b)
+          return;
+
+        m_connected.insert (i, b);
+        m_listLock.clear ();
     }
 
     void RemoveInvalidRefs();