diff --git a/libsrc/geom2d/csg2d.cpp b/libsrc/geom2d/csg2d.cpp
index e1168d53..f46a813d 100644
--- a/libsrc/geom2d/csg2d.cpp
+++ b/libsrc/geom2d/csg2d.cpp
@@ -670,55 +670,49 @@ void AddIntersectionPoint(Edge edgeP, Edge edgeQ, IntersectionType i, double alp
   }
 }
 
-void ComputeIntersections(Solid2d & s1, Solid2d & s2)
+void ComputeIntersections(Loop & l1, Loop & l2)
 {
-  static Timer tall("ComputeIntersections"); RegionTimer rtall(tall);
-  static Timer t_tree("build search trees");
   static Timer t_intersect("find intersections");
   static Timer t_split("split splines");
-  auto & PP = s1.polys;
-  auto & QQ = s2.polys;
 
   t_intersect.Start();
-  for (Loop& P : PP)
-    for (Edge edgeP : P.Edges(SOURCE))
-      for (Loop& Q : QQ)
-        for (Edge edgeQ : Q.Edges(SOURCE))
+  for (Edge edgeP : l1.Edges(SOURCE))
+    for (Edge edgeQ : l2.Edges(SOURCE))
+    {
+      double alpha = 0.0;
+      double beta = 0.0;
+      IntersectionType i = intersect(edgeP, edgeQ, alpha, beta);
+      AddIntersectionPoint(edgeP, edgeQ, i, alpha, beta);
+      if(i==X_INTERSECTION && (edgeP.v0->spline || edgeQ.v0->spline))
+      {
+        double alpha1 = alpha+1e2*EPSILON;
+        double beta1 = 0.0; //beta+1e2*EPSILON;
+
+        // search for possible second intersection
+        i = intersect(edgeP, edgeQ, alpha1, beta1);
+        // cout << "second intersection " << i << ',' << alpha1 << ',' << beta1 << ',' << alpha1-alpha << ',' << beta1-beta << endl;
+        if(i!=NO_INTERSECTION && alpha+EPSILON<alpha1)
         {
-          double alpha = 0.0;
-          double beta = 0.0;
-          IntersectionType i = intersect(edgeP, edgeQ, alpha, beta);
-          AddIntersectionPoint(edgeP, edgeQ, i, alpha, beta);
-          if(i==X_INTERSECTION && (edgeP.v0->spline || edgeQ.v0->spline))
+          // Add midpoint of two intersection points to avoid false overlap detection of splines
+          // TODO: Check if this is really necessary
+          auto alpha_mid = 0.5*(alpha+alpha1);
+          auto beta_mid = 0.5*(beta+beta1);
+          Point<2> MP;
+          if(edgeP.v0->spline)
           {
-            double alpha1 = alpha+1e2*EPSILON;
-            double beta1 = 0.0; //beta+1e2*EPSILON;
-
-            // search for possible second intersection
-            i = intersect(edgeP, edgeQ, alpha1, beta1);
-            // cout << "second intersection " << i << ',' << alpha1 << ',' << beta1 << ',' << alpha1-alpha << ',' << beta1-beta << endl;
-            if(i!=NO_INTERSECTION && alpha+EPSILON<alpha1)
-            {
-              // Add midpoint of two intersection points to avoid false overlap detection of splines
-              // TODO: Check if this is really necessary
-              auto alpha_mid = 0.5*(alpha+alpha1);
-              auto beta_mid = 0.5*(beta+beta1);
-              Point<2> MP;
-              if(edgeP.v0->spline)
-              {
-                MP = edgeP.v0->spline->GetPoint(alpha_mid);
-                edgeP.v0->Insert(MP, alpha_mid);
-              }
-              else
-                MP = edgeQ.v0->spline->GetPoint(beta_mid);
-
-              if(edgeQ.v0->spline)
-                edgeQ.v0->Insert(MP, beta_mid);
-
-              AddIntersectionPoint(edgeP, edgeQ, i, alpha1, beta1);
-            }
+            MP = edgeP.v0->spline->GetPoint(alpha_mid);
+            edgeP.v0->Insert(MP, alpha_mid);
           }
+          else
+            MP = edgeQ.v0->spline->GetPoint(beta_mid);
+
+          if(edgeQ.v0->spline)
+            edgeQ.v0->Insert(MP, beta_mid);
+
+          AddIntersectionPoint(edgeP, edgeQ, i, alpha1, beta1);
         }
+      }
+    }
   t_intersect.Stop();
 
   RegionTimer rt_split(t_split);
@@ -743,12 +737,19 @@ void ComputeIntersections(Solid2d & s1, Solid2d & s2)
     } while(!curr->is_source);
   };
 
-  for (Loop& P : PP)
-    for (Vertex* v : P.Vertices(SOURCE))
-      split_spline_at_vertex(v);
-  for (Loop& Q : QQ)
-    for (Vertex* v : Q.Vertices(SOURCE))
-      split_spline_at_vertex(v);
+  for (Vertex* v : l1.Vertices(SOURCE))
+    split_spline_at_vertex(v);
+  for (Vertex* v : l2.Vertices(SOURCE))
+    split_spline_at_vertex(v);
+}
+
+void ComputeIntersections(Solid2d & s1, Solid2d & s2)
+{
+  static Timer tall("ComputeIntersections"); RegionTimer rtall(tall);
+
+  for (Loop& l1 : s1.polys)
+    for (Loop& l2 : s2.polys)
+      ComputeIntersections(l1, l2);
 }
 
 enum RelativePositionType
@@ -1251,20 +1252,25 @@ void CleanUpResult(Solid2d & sr)
       RR.RemoveElement(i);
 }
 
+void RemoveDuplicates(Loop & poly)
+{
+  if(poly.first==nullptr)
+    return;
+
+  Vertex * last = poly.first->prev;
+  for(auto v : poly.Vertices(ALL))
+  {
+    if(Dist2(*v, *last)<EPSILON*EPSILON)
+      poly.Remove(last);
+    last = v;
+  }
+}
+
 void RemoveDuplicates(Solid2d & sr)
 {
   static Timer tall("RemoveDuplicates"); RegionTimer rtall(tall);
   for(auto & poly : sr.polys)
-  {
-    if(poly.first==nullptr) continue;
-    Vertex * last = poly.first->prev;
-    for(auto v : poly.Vertices(ALL))
-    {
-      if(Dist2(*v, *last)<EPSILON*EPSILON)
-        poly.Remove(last);
-      last = v;
-    }
-  }
+    RemoveDuplicates(poly);
 }
 
 Loop RectanglePoly(double x0, double x1, double y0, double y1, string bc)
@@ -1316,6 +1322,14 @@ void AddIntersectionPoints ( Solid2d & s1, Solid2d & s2 )
   RemoveDuplicates(s2);
 }
 
+void AddIntersectionPoints ( Loop & l1, Loop & l2 )
+{
+  ComputeIntersections(l1, l2);
+  RemoveDuplicates(l1);
+  RemoveDuplicates(l2);
+}
+
+
 Solid2d ClipSolids ( const Solid2d & s1, const Solid2d & s2, char op)
 {
   return ClipSolids(Solid2d{s1}, Solid2d{s2}, op);
@@ -1725,6 +1739,7 @@ shared_ptr<netgen::SplineGeometry2d> CSG2d :: GenerateSplineGeometry()
   static Timer t_is_inside("is inside check");
   static Timer t_segments("add segments");
   static Timer t_intersections("add intersections");
+  static Timer t_segtree("seg trees");
   RegionTimer rt(tall);
 
   struct Seg
@@ -1756,18 +1771,27 @@ shared_ptr<netgen::SplineGeometry2d> CSG2d :: GenerateSplineGeometry()
       box.Add(sbox.PMax());
     }
 
-  netgen::BoxTree <2, int> solid_tree(box);
+  netgen::BoxTree <2> solid_tree(box);
+  Array<INT<2>> loop_list;
 
   for(auto i : Range(solids))
-      solid_tree.Insert(solids[i].GetBoundingBox(), i);
+    for(auto li : Range(solids[i].polys))
+    {
+      solid_tree.Insert(solids[i].polys[li].GetBoundingBox(), loop_list.Size());
+      loop_list.Append(INT<2>(i, li));
+    }
 
   for(auto i1 : Range(solids))
+    for(auto li1 : Range(solids[i1].polys))
     {
-      auto sbox = solids[i1].GetBoundingBox();
-      solid_tree.GetFirstIntersecting(sbox.PMin(), sbox.PMax(), [&] (int i2)
+      auto & poly1 = solids[i1].polys[li1];
+      auto box = poly1.GetBoundingBox();
+      solid_tree.GetFirstIntersecting(box.PMin(), box.PMax(), [&] (int ii)
         {
+          auto i2 = loop_list[ii][0];
+          auto li2 = loop_list[ii][1];
           if(i1<i2)
-            AddIntersectionPoints(solids[i1], solids[i2]);
+            AddIntersectionPoints(poly1, solids[i2].polys[li2]);
           return false;
         });
     }