diff --git a/libs/ardour/ardour/location.h b/libs/ardour/ardour/location.h
index 8889ca39af..9a1d497567 100644
--- a/libs/ardour/ardour/location.h
+++ b/libs/ardour/ardour/location.h
@@ -301,6 +301,7 @@ public:
 	timepos_t first_mark_after (timepos_t const &, bool include_special_ranges = false);
 
 	Location* next_section (Location*, timepos_t&, timepos_t&) const;
+	Location* next_section_iter (Location*, timepos_t&, timepos_t&, std::vector<LocationPair>& cache) const;
 	Location* section_at (timepos_t const&, timepos_t&, timepos_t&) const;
 
 	void marks_either_side (timepos_t const &, timepos_t &, timepos_t &) const;
diff --git a/libs/ardour/location.cc b/libs/ardour/location.cc
index d0cb25800d..c10fc816a0 100644
--- a/libs/ardour/location.cc
+++ b/libs/ardour/location.cc
@@ -1597,8 +1597,18 @@ Locations::sorted_section_locations (vector<LocationPair>& locs) const
 Location*
 Locations::next_section (Location* l, timepos_t& start, timepos_t& end) const
 {
-	vector<LocationPair> locs;
-	sorted_section_locations (locs);
+	std::vector<Locations::LocationPair> locs;
+	return next_section_iter (l, start, end, locs);
+}
+
+Location*
+Locations::next_section_iter (Location* l, timepos_t& start, timepos_t& end, vector<LocationPair>& locs) const
+{
+	if (!l) {
+		/* build cache */
+		locs.clear ();
+		sorted_section_locations (locs);
+	}
 
 	if (locs.size () < 2) {
 		return NULL;