From 9219781ce0f3f317ad5423c9dcd3a3500dedc0aa Mon Sep 17 00:00:00 2001
From: supermerill <merill@fr.fr>
Date: Mon, 18 Feb 2019 17:01:29 +0100
Subject: [PATCH] perf improvement for extra_periemters

---
 src/libslic3r/PerimeterGenerator.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index 529153dea..5bf74060a 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -218,8 +218,8 @@ void PerimeterGenerator::process()
                 // improvement for future: find a way to add perimeters only where it's needed.
                 bool has_overhang = false;
                 if (this->config->extra_perimeters && !last.empty() && !overhangs_unsupported.empty()) {
-                    size_t unsupported_test = intersection(overhangs_unsupported, last).size();
-                    if (unsupported_test > 0) {
+                    overhangs_unsupported = intersection_ex(overhangs_unsupported, last);
+                    if (overhangs_unsupported.size() > 0) {
                         //add fake perimeters here
                         has_overhang = true;
                     }