From: Fabian Vogt <fabian@ritter-vogt.de>
Subject: Workaround for high load due to animated tray icons
References: kde#356479

When a tray icon name changes, it always does a full lookup, which is expensive.
Add a small QHash as cache to work around this.

diff --git a/applets/systemtray/systemtray.cpp b/applets/systemtray/systemtray.cpp
index 66bb5b4..f440ff0 100644
--- a/applets/systemtray/systemtray.cpp
+++ b/applets/systemtray/systemtray.cpp
@@ -127,8 +127,13 @@ void SystemTray::cleanupTask(const QString &task)
 
 QVariant SystemTray::resolveIcon(const QVariant &variant, const QString &iconThemePath)
 {
+	static QHash<QString, QVariant> cache;
     if (variant.canConvert<QString>()) {
         if (!iconThemePath.isEmpty()) {
+            auto i = cache.find(variant.toString() + iconThemePath);
+            if(i != cache.end())
+		return i.value();
+		qCWarning(SYSTEM_TRAY) << "Cache not hit" << iconThemePath;
             const QString path = iconThemePath;
             if (!path.isEmpty()) {
                 // FIXME: If last part of path is not "icons", this won't work!
@@ -136,7 +141,9 @@ QVariant SystemTray::resolveIcon(const QVariant &variant, const QString &iconThe
                 if (tokens.length() >= 3 && tokens.takeLast() == QLatin1String("icons")) {
                     const QString appName = tokens.takeLast().toString();
 
-                    return QVariant(QIcon(new AppIconEngine(variant.toString(), path, appName)));
+                    auto v = QVariant(QIcon(new AppIconEngine(variant.toString(), path, appName)));
+                    cache.insert(variant.toString() + iconThemePath, v);
+                    return v;
                 } else {
                     qCWarning(SYSTEM_TRAY) << "Wrong IconThemePath" << path << ": too short or does not end with 'icons'";
                 }