From a34cd6912530417819c91ba312c485ea78f1da0c Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Mon, 2 Mar 2020 10:06:16 +0100
Subject: [PATCH] PartDesign: [skip ci] fixes #0004276: Loading a project takes
 much more time compared to previous versions

---
 src/Mod/PartDesign/App/FeatureDressUp.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/Mod/PartDesign/App/FeatureDressUp.cpp b/src/Mod/PartDesign/App/FeatureDressUp.cpp
index 59f748d4cc..d9f332a44e 100644
--- a/src/Mod/PartDesign/App/FeatureDressUp.cpp
+++ b/src/Mod/PartDesign/App/FeatureDressUp.cpp
@@ -177,7 +177,12 @@ void DressUp::onChanged(const App::Property* prop)
             BaseFeature.setValue (Base.getValue());
         }
     } else if (prop == &Shape || prop == &SupportTransform) {
-        if (!isRestoring() && !getDocument()->isPerformingTransaction()) {
+        // This is an expensive operation and to avoid to perform it unnecessarily it's not sufficient
+        // to check for the 'Restore' flag of the dress-up feature because at that time it's already reset.
+        // Instead the 'Restore' flag of the document must be checked.
+        // For more details see: https://forum.freecadweb.org/viewtopic.php?f=3&t=43799 (and issue 4276)
+        if (!getDocument()->testStatus(App::Document::Restoring) &&
+            !getDocument()->isPerformingTransaction()) {
             Part::TopoShape s;
             auto base = Base::freecad_dynamic_cast<FeatureAddSub>(getBaseObject(true));
             if(!base) {