diff --git a/src/db/db/dbDeepRegion.cc b/src/db/db/dbDeepRegion.cc
index f38d94228..b76dc34ef 100644
--- a/src/db/db/dbDeepRegion.cc
+++ b/src/db/db/dbDeepRegion.cc
@@ -1648,6 +1648,7 @@ DeepRegion::run_check (db::edge_relation_type rel, bool different_polygons, cons
   bool other_is_merged = true;
 
   bool needs_merged_primary = different_polygons || options.needs_merged ();
+needs_merged_primary = true; // @@@
   bool primary_is_merged = ! merged_semantics () || needs_merged_primary || is_merged ();
 
   if (other == subject_regionptr ()) {
diff --git a/src/db/db/dbHash.h b/src/db/db/dbHash.h
index 9ed98ae0b..19913d2c0 100644
--- a/src/db/db/dbHash.h
+++ b/src/db/db/dbHash.h
@@ -253,7 +253,8 @@ namespace std
     h = hfunc_coord (o.end_ext (), h);
     h = hfunc_coord (o.width (), h);
     //  NOTE: using too many points for the hash function just slows down the code.
-    unsigned int n = 20;
+    // @@@ unsigned int n = 20;
+    unsigned int n = std::numeric_limits<unsigned int>::max (); // @@@
     for (typename db::path<C>::iterator p = o.begin (); p != o.end (); ++p) {
       if (--n == 0) {
         h = hfunc (o.points (), h);
@@ -288,7 +289,8 @@ namespace std
   size_t hfunc (const db::polygon_contour<C> &o, size_t h)
   {
     //  NOTE: using too many points for the hash function just slows down the code.
-    unsigned int n = 20;
+    // @@@ unsigned int n = 20;
+    unsigned int n = std::numeric_limits<unsigned int>::max (); // @@@
     for (typename db::polygon_contour<C>::simple_iterator i = o.begin (); i != o.end (); ++i) {
       if (--n == 0) {
         h = hfunc (o.size (), h);
@@ -324,7 +326,8 @@ namespace std
   {
     h = hfunc (o.hull (), h);
     //  NOTE: using too many points for the hash function just slows down the code.
-    unsigned int n = 20;
+    // @@@ unsigned int n = 20;
+    unsigned int n = std::numeric_limits<unsigned int>::max (); // @@@
     for (size_t i = 0; i < o.holes (); ++i) {
       if (--n == 0) {
         h = hfunc (o.holes (), h);
diff --git a/src/db/db/dbHierProcessor.cc b/src/db/db/dbHierProcessor.cc
index fc96f6cd9..1afbff8ca 100644
--- a/src/db/db/dbHierProcessor.cc
+++ b/src/db/db/dbHierProcessor.cc
@@ -342,11 +342,11 @@ template <class TS, class TI, class TR>
 local_processor_cell_context<TS, TI, TR> &
 local_processor_cell_context<TS, TI, TR>::operator= (const local_processor_cell_context &other)
 {
-    if (this != &other) {
-        m_propagated = other.m_propagated;
-        m_drops = other.m_drops;
-    }
-    return *this;
+  if (this != &other) {
+    m_propagated = other.m_propagated;
+    m_drops = other.m_drops;
+  }
+  return *this;
 }
 
 template <class TS, class TI, class TR>
@@ -1221,6 +1221,7 @@ private:
     db::box_convert <db::CellInst, true> inst_bc (*mp_subject_layout, m_subject_layer);
     db::Box rbox = db::box_convert<TI> () (ref);
 
+// @@@ make member of receiver?
     db::shape_reference_translator_with_trans<TI, db::ICplxTrans> rt (mp_subject_layout);
 
     for (db::CellInstArray::iterator n = inst->begin_touching (safe_box_enlarged (rbox, dist - 1, dist - 1), inst_bc); ! n.at_end (); ++n) {
diff --git a/src/db/db/dbRegionLocalOperations.cc b/src/db/db/dbRegionLocalOperations.cc
index cd4f9ea1c..4be8ca7a1 100644
--- a/src/db/db/dbRegionLocalOperations.cc
+++ b/src/db/db/dbRegionLocalOperations.cc
@@ -250,7 +250,7 @@ check_local_operation<TS, TI>::do_compute_local (db::Layout *layout, const shape
 
     size_t n = 0;
 
-    if (m_is_merged) {
+    if (m_is_merged || (interactions.size () == 1 && interactions.subject_shape (interactions.begin ()->first).is_box ())) {
 
       for (typename shape_interactions<TS, TI>::iterator i = interactions.begin (); i != interactions.end (); ++i) {
         const TS &subject = interactions.subject_shape (i->first);
@@ -355,7 +355,7 @@ check_local_operation<TS, TI>::do_compute_local (db::Layout *layout, const shape
 
     size_t n = 0;
 
-    if (m_is_merged) {
+    if (m_is_merged || (interactions.size () == 1 && ids.empty () && interactions.subject_shape (interactions.begin ()->first).is_box ())) {
 
       for (typename shape_interactions<TS, TI>::iterator i = interactions.begin (); i != interactions.end (); ++i) {
         //  we can't directly insert because TS may be != TI