diff --git a/libtaskmanager/xwindowtasksmodel.cpp b/libtaskmanager/xwindowtasksmodel.cpp
--- a/libtaskmanager/xwindowtasksmodel.cpp
+++ b/libtaskmanager/xwindowtasksmodel.cpp
@@ -61,6 +61,7 @@
     QMultiHash<WId, WId> transientsDemandingAttention;
     QHash<WId, KWindowInfo*> windowInfoCache;
     QHash<WId, AppData> appDataCache;
+    QHash<WId, QUrl> m_urlFromMetadataCache;
     QHash<WId, QRect> delegateGeometries;
     QSet<WId> usingFallbackIcon;
     WId activeWindow = -1;
@@ -254,6 +255,7 @@
         appDataCache.remove(window);
         usingFallbackIcon.remove(window);
         delegateGeometries.remove(window);
+        m_urlFromMetadataCache.remove(window);
         q->endRemoveRows();
     } else { // Could be a transient.
         // Removing a transient might change the demands attention state of the leader.
@@ -402,7 +404,7 @@
 
 KWindowInfo* XWindowTasksModel::Private::windowInfo(WId window)
 {
-    const auto &it = windowInfoCache.constFind(window);
+    const auto it = windowInfoCache.constFind(window);
 
     if (it != windowInfoCache.constEnd()) {
         return *it;
@@ -416,7 +418,7 @@
 
 AppData XWindowTasksModel::Private::appData(WId window)
 {
-    const auto &it = appDataCache.constFind(window);
+    const auto it = appDataCache.constFind(window);
 
     if (it != appDataCache.constEnd()) {
         return *it;
@@ -504,9 +506,18 @@
         }
     }
 
-    return windowUrlFromMetadata(info->windowClassClass(),
+    // Use a cache, windowUrlFromMetadata is quite expensive and can be called too many times.
+    const auto it = m_urlFromMetadataCache.constFind(window);
+
+    if (it != m_urlFromMetadataCache.constEnd()) {
+        return *it;
+    }
+
+    const auto url = windowUrlFromMetadata(info->windowClassClass(),
         NETWinInfo(QX11Info::connection(), window, QX11Info::appRootWindow(), NET::WMPid, 0).pid(),
         rulesConfig, info->windowClassName());
+    m_urlFromMetadataCache.insert(window, url);
+    return url;
 }
 
 QUrl XWindowTasksModel::Private::launcherUrl(WId window, bool encodeFallbackIcon)
@@ -574,11 +585,11 @@
     } else if (role == Qt::DecorationRole) {
         return d->icon(window);
     } else if (role == AppId) {
-        return d->appData(window).id;
+        return d->windowInfo(window)->windowClassClass();
     } else if (role == AppName) {
-        return d->appData(window).name;
+        return d->windowInfo(window)->name();
     } else if (role == GenericName) {
-        return d->appData(window).genericName;
+        return d->windowInfo(window)->windowClassName();
     } else if (role == LauncherUrl) {
         return d->launcherUrl(window);
     } else if (role == LauncherUrlWithoutIcon) {