3 files changed, 30 insertions, 3 deletions
diff --git a/src/kitemviews/kitemlistcontroller.cpp b/src/kitemviews/kitemlistcontroller.cpp
index 130936488..7af8781b4 100644
--- a/src/kitemviews/kitemlistcontroller.cpp
+++ b/src/kitemviews/kitemlistcontroller.cpp
@@ -849,6 +849,9 @@ bool KItemListController::dragEnterEvent(QGraphicsSceneDragDropEvent* event, con
 {
     Q_UNUSED(event);
     Q_UNUSED(transform);
+
+    DragAndDropHelper::clearUrlListMatchesUrlCache();
+
     return false;
 }
 
diff --git a/src/views/draganddrophelper.cpp b/src/views/draganddrophelper.cpp
index e944227df..4d76992ca 100644
--- a/src/views/draganddrophelper.cpp
+++ b/src/views/draganddrophelper.cpp
@@ -29,12 +29,21 @@
 #include <KIO/DropJob>
 #include <KJobWidgets>
 
+QHash<QUrl, bool> DragAndDropHelper::m_urlListMatchesUrlCache;
 
 bool DragAndDropHelper::urlListMatchesUrl(const QList<QUrl>& urls, const QUrl& destUrl)
 {
-    return std::find_if(urls.constBegin(), urls.constEnd(), [destUrl](const QUrl& url) {
-        return url.matches(destUrl, QUrl::StripTrailingSlash);
-    }) != urls.constEnd();
+    auto iteratorResult = m_urlListMatchesUrlCache.constFind(destUrl);
+    if (iteratorResult != m_urlListMatchesUrlCache.constEnd()) {
+        return *iteratorResult;
+    }
+
+    const bool destUrlMatches =
+        std::find_if(urls.constBegin(), urls.constEnd(), [destUrl](const QUrl& url) {
+            return url.matches(destUrl, QUrl::StripTrailingSlash);
+        }) != urls.constEnd();
+
+    return *m_urlListMatchesUrlCache.insert(destUrl, destUrlMatches);
 }
 
 KIO::DropJob* DragAndDropHelper::dropUrls(const QUrl& destUrl, QDropEvent* event, QWidget* window)
@@ -63,3 +72,8 @@ KIO::DropJob* DragAndDropHelper::dropUrls(const QUrl& destUrl, QDropEvent* event
     return nullptr;
 }
 
+void DragAndDropHelper::clearUrlListMatchesUrlCache()
+{
+    DragAndDropHelper::m_urlListMatchesUrlCache.clear();
+}
+
diff --git a/src/views/draganddrophelper.h b/src/views/draganddrophelper.h
index e47f83ca8..0c7eadc6c 100644
--- a/src/views/draganddrophelper.h
+++ b/src/views/draganddrophelper.h
@@ -54,6 +54,16 @@ public:
      * @return True if destUrl is contained in the urls parameter.
      */
     static bool urlListMatchesUrl(const QList<QUrl>& urls, const QUrl& destUrl);
+
+    /**
+     * clear the internal cache.
+     */
+    static void clearUrlListMatchesUrlCache();
+private:
+    /**
+     * Stores the results of the expensive checks made in urlListMatchesUrl.
+     */
+    static QHash<QUrl, bool> m_urlListMatchesUrlCache;
 };
 
 #endif