diff --git a/src/bittorrent.cpp b/src/bittorrent.cpp
index 7a4358884..3df758137 100644
--- a/src/bittorrent.cpp
+++ b/src/bittorrent.cpp
@@ -822,8 +822,9 @@ QTorrentHandle Bittorrent::addMagnetUri(QString magnet_uri, bool resumed) {
   //Getting fast resume data if existing
   std::vector<char> buf;
   if(resumed) {
-    qDebug("Trying to load fastresume data: %s", qPrintable(torrentBackup.path()+QDir::separator()+hash+QString(".fastresume")));
-    if (load_file((torrentBackup.path()+QDir::separator()+hash+QString(".fastresume")).toLocal8Bit().constData(), buf) == 0) {
+    const QString &fastresume_path = torrentBackup.path()+QDir::separator()+hash+QString(".fastresume");
+    qDebug("Trying to load fastresume data: %s", qPrintable(fastresume_path));
+    if (load_file(fastresume_path.toLocal8Bit().constData(), buf) == 0) {
       fastResume = true;
       p.resume_data = &buf;
       qDebug("Successfuly loaded");
@@ -1030,8 +1031,9 @@ QTorrentHandle Bittorrent::addTorrent(QString path, bool fromScanDir, QString fr
   //Getting fast resume data if existing
   std::vector<char> buf;
   if(resumed) {
-    qDebug("Trying to load fastresume data: %s", qPrintable(torrentBackup.path()+QDir::separator()+hash+QString(".fastresume")));
-    if (load_file((torrentBackup.path()+QDir::separator()+hash+QString(".fastresume")).toLocal8Bit().constData(), buf) == 0) {
+    const QString &fastresume_path = torrentBackup.path()+QDir::separator()+hash+QString(".fastresume");
+    qDebug("Trying to load fastresume data: %s", qPrintable(fastresume_path));
+    if (load_file(fastresume_path.toLocal8Bit().constData(), buf) == 0) {
       fastResume = true;
       p.resume_data = &buf;
       qDebug("Successfuly loaded");
@@ -1315,7 +1317,8 @@ void Bittorrent::enableLSD(bool b) {
 }
 
 void Bittorrent::loadSessionState() {
-  boost::filesystem::ifstream ses_state_file((misc::cacheLocation()+QDir::separator()+QString::fromUtf8("ses_state")).toLocal8Bit().constData()
+  const QString &state_path = misc::cacheLocation()+QDir::separator()+QString::fromUtf8("ses_state");
+  boost::filesystem::ifstream ses_state_file(state_path.toLocal8Bit().constData()
                                              , std::ios_base::binary);
   ses_state_file.unsetf(std::ios_base::skipws);
   s->load_state(bdecode(
@@ -1326,7 +1329,8 @@ void Bittorrent::loadSessionState() {
 void Bittorrent::saveSessionState() {
   qDebug("Saving session state to disk...");
   entry session_state = s->state();
-  boost::filesystem::ofstream out((misc::cacheLocation()+QDir::separator()+QString::fromUtf8("ses_state")).toLocal8Bit().constData()
+  const QString &state_path = misc::cacheLocation()+QDir::separator()+QString::fromUtf8("ses_state");
+  boost::filesystem::ofstream out(state_path.toLocal8Bit().constData()
                                   , std::ios_base::binary);
   out.unsetf(std::ios_base::skipws);
   bencode(std::ostream_iterator<char>(out), session_state);
@@ -2217,7 +2221,8 @@ void Bittorrent::addConsoleMessage(QString msg, QString) {
     if(DHTEnabled) {
       try{
         entry dht_state = s->dht_state();
-        boost::filesystem::ofstream out((misc::cacheLocation()+QDir::separator()+QString::fromUtf8("dht_state")).toLocal8Bit().constData(), std::ios_base::binary);
+        const QString &dht_path = misc::cacheLocation()+QDir::separator()+QString::fromUtf8("dht_state");
+        boost::filesystem::ofstream out(dht_path.toLocal8Bit().constData(), std::ios_base::binary);
         out.unsetf(std::ios_base::skipws);
         bencode(std::ostream_iterator<char>(out), dht_state);
         qDebug("DHT entry saved");
diff --git a/src/downloadthread.cpp b/src/downloadthread.cpp
index f65593f26..0bcf79145 100644
--- a/src/downloadthread.cpp
+++ b/src/downloadthread.cpp
@@ -117,7 +117,7 @@ void downloadThread::applyProxySettings() {
     QString IP = settings.value(QString::fromUtf8("Preferences/Connection/HTTPProxy/IP"), "0.0.0.0").toString();
     proxy.setHostName(IP);
     QString port = settings.value(QString::fromUtf8("Preferences/Connection/HTTPProxy/Port"), 8080).toString();
-    qDebug("Using proxy: %s", qPrintable(IP+QString(":")+port));
+    qDebug("Using proxy: %s", qPrintable(IP));
     proxy.setPort(port.toUShort());
     // Default proxy type is HTTP, we must change if it is SOCKS5
     if(intValue == SOCKS5 || intValue == SOCKS5_PW) {
diff --git a/src/eventmanager.cpp b/src/eventmanager.cpp
index 814a64b61..923f7b044 100644
--- a/src/eventmanager.cpp
+++ b/src/eventmanager.cpp
@@ -295,23 +295,23 @@ QVariantMap EventManager::getPropGeneralInfo(QString hash) const {
     data["creation_date"] = h.creation_date();
     // Comment
     data["comment"] = h.comment();
-    data["total_wasted"] = misc::friendlyUnit(h.total_failed_bytes()+h.total_redundant_bytes());
-    data["total_uploaded"] = misc::friendlyUnit(h.all_time_upload()) + " ("+misc::friendlyUnit(h.total_payload_upload())+" "+tr("this session")+")";
-    data["total_downloaded"] = misc::friendlyUnit(h.all_time_download()) + " ("+misc::friendlyUnit(h.total_payload_download())+" "+tr("this session")+")";
+    data["total_wasted"] = QVariant(misc::friendlyUnit(h.total_failed_bytes()+h.total_redundant_bytes()));
+    data["total_uploaded"] = QVariant(misc::friendlyUnit(h.all_time_upload()) + " ("+misc::friendlyUnit(h.total_payload_upload())+" "+tr("this session")+")");
+    data["total_downloaded"] = QVariant(misc::friendlyUnit(h.all_time_download()) + " ("+misc::friendlyUnit(h.total_payload_download())+" "+tr("this session")+")");
     if(h.upload_limit() <= 0)
       data["up_limit"] = QString::fromUtf8("∞");
     else
-      data["up_limit"] = misc::friendlyUnit(h.upload_limit())+tr("/s", "/second (i.e. per second)");
+      data["up_limit"] = QVariant(misc::friendlyUnit(h.upload_limit())+tr("/s", "/second (i.e. per second)"));
     if(h.download_limit() <= 0)
       data["dl_limit"] = QString::fromUtf8("∞");
     else
-      data["dl_limit"] =  misc::friendlyUnit(h.download_limit())+tr("/s", "/second (i.e. per second)");
+      data["dl_limit"] =  QVariant(misc::friendlyUnit(h.download_limit())+tr("/s", "/second (i.e. per second)"));
     QString elapsed_txt = misc::userFriendlyDuration(h.active_time());
     if(h.is_seed()) {
       elapsed_txt += " ("+tr("Seeded for %1", "e.g. Seeded for 3m10s").arg(misc::userFriendlyDuration(h.seeding_time()))+")";
     }
     data["time_elapsed"] = elapsed_txt;
-    data["nb_connections"] = QString::number(h.num_connections())+" ("+tr("%1 max", "e.g. 10 max").arg(QString::number(h.connections_limit()))+")";
+    data["nb_connections"] = QVariant(QString::number(h.num_connections())+" ("+tr("%1 max", "e.g. 10 max").arg(QString::number(h.connections_limit()))+")");
     // Update ratio info
     double ratio = BTSession->getRealRatio(h.hash());
     if(ratio > 100.)
diff --git a/src/misc.h b/src/misc.h
index 102d83c86..bccfb0da2 100644
--- a/src/misc.h
+++ b/src/misc.h
@@ -329,7 +329,8 @@ public:
 #ifndef Q_WS_WIN
     unsigned long long available;
     struct statfs stats;
-    const int ret = statfs ((dir_path.path()+"/.").toLocal8Bit().data(), &stats) ;
+    const QString &statfs_path = dir_path.path()+"/.";
+    const int ret = statfs (qPrintable(statfs_path), &stats) ;
     if(ret == 0) {
       available = ((unsigned long long)stats.f_bavail) *
                   ((unsigned long long)stats.f_bsize) ;
diff --git a/src/peerlistwidget.cpp b/src/peerlistwidget.cpp
index a75f26008..8446afbdd 100644
--- a/src/peerlistwidget.cpp
+++ b/src/peerlistwidget.cpp
@@ -279,7 +279,7 @@ void PeerListWidget::saveSettings() const {
   else
     sortOrderLetter = QString::fromUtf8("d");
   int index = header()->sortIndicatorSection();
-  settings.setValue(QString::fromUtf8("TorrentProperties/Peers/PeerListSortedCol"), QString::number(index)+sortOrderLetter);
+  settings.setValue(QString::fromUtf8("TorrentProperties/Peers/PeerListSortedCol"), QVariant(QString::number(index)+sortOrderLetter));
 }
 
 void PeerListWidget::loadPeers(const QTorrentHandle &h, bool force_hostname_resolution) {
diff --git a/src/preferences.h b/src/preferences.h
index ceff41231..bfea695f9 100644
--- a/src/preferences.h
+++ b/src/preferences.h
@@ -121,11 +121,7 @@ public:
   // Downloads
   static QString getSavePath() {
     QSettings settings("qBittorrent", "qBittorrent");
-    QString home = QDir::homePath();
-    if(home[home.length()-1] != QDir::separator()){
-      home += QDir::separator();
-    }
-    return settings.value(QString::fromUtf8("Preferences/Downloads/SavePath"), home+"qBT_dir").toString();
+    return settings.value(QString::fromUtf8("Preferences/Downloads/SavePath"), QDir::home().absoluteFilePath("qBT_dir")).toString();
   }
 
   static void setSavePath(QString save_path) {
@@ -145,8 +141,8 @@ public:
 
   static QString getTempPath() {
     QSettings settings("qBittorrent", "qBittorrent");
-    QString home = QDir::homePath();
-    return settings.value(QString::fromUtf8("Preferences/Downloads/TempPath"), home+"qBT_dir"+QDir::separator()+"temp").toString();
+    QString temp = QDir::home().absoluteFilePath("qBT_dir")+QDir::separator()+"temp";
+    return settings.value(QString::fromUtf8("Preferences/Downloads/TempPath"), temp).toString();
   }
 
   static void setTempPath(QString path) {
diff --git a/src/propertieswidget.cpp b/src/propertieswidget.cpp
index 6c9a04dd9..56f90a7cc 100644
--- a/src/propertieswidget.cpp
+++ b/src/propertieswidget.cpp
@@ -293,7 +293,7 @@ void PropertiesWidget::saveSettings() {
     sizes = slideSizes;
   qDebug("Sizes: %d", sizes.size());
   if(sizes.size() == 2) {
-    settings.setValue(QString::fromUtf8("TorrentProperties/SplitterSizes"), QString::number(sizes.first())+','+QString::number(sizes.last()));
+    settings.setValue(QString::fromUtf8("TorrentProperties/SplitterSizes"), QVariant(QString::number(sizes.first())+','+QString::number(sizes.last())));
   }
 }
 
@@ -480,7 +480,7 @@ void PropertiesWidget::openDoubleClickedFile(QModelIndex index) {
     h.flush_cache();
 #endif
     if(QFile::exists(file_path))
-      QDesktopServices::openUrl("file://"+file_path);
+      QDesktopServices::openUrl(QUrl("file://"+file_path));
     else
       QMessageBox::warning(this, tr("I/O Error"), tr("This file does not exist yet."));
   } else {
@@ -501,7 +501,7 @@ void PropertiesWidget::openDoubleClickedFile(QModelIndex index) {
     h.flush_cache();
 #endif
     if(QFile::exists(file_path))
-      QDesktopServices::openUrl("file://"+file_path);
+      QDesktopServices::openUrl(QUrl("file://"+file_path));
     else
       QMessageBox::warning(this, tr("I/O Error"), tr("This folder does not exist yet."));
   }
diff --git a/src/rss_imp.cpp b/src/rss_imp.cpp
index 00d2be2a0..ef4dc55bc 100644
--- a/src/rss_imp.cpp
+++ b/src/rss_imp.cpp
@@ -405,7 +405,7 @@ void RSSImp::fillFeedsList(QTreeWidgetItem *parent, RssFolder *rss_parent) {
       item = new QTreeWidgetItem(listStreams);
     else
       item = new QTreeWidgetItem(parent);
-    item->setData(0, Qt::DisplayRole, rss_child->getName()+ QString::fromUtf8("  (")+QString::number(rss_child->getNbUnRead(), 10)+QString(")"));
+    item->setData(0, Qt::DisplayRole, QVariant(rss_child->getName()+ QString::fromUtf8("  (")+QString::number(rss_child->getNbUnRead(), 10)+QString(")")));
     // Notify TreeWidget of item addition
     listStreams->itemAdded(item, rss_child);
     // Set Icon
diff --git a/src/searchengine.cpp b/src/searchengine.cpp
index 47470f965..f953fcbd7 100644
--- a/src/searchengine.cpp
+++ b/src/searchengine.cpp
@@ -432,14 +432,15 @@ void SearchEngine::updateNova() {
     QString shipped_file = shipped_subDir.path()+"/"+file;
     // Copy python classes
     if(file.endsWith(".py")) {
-      if(getPluginVersion(shipped_file) > getPluginVersion(destDir+file) ) {
+      const QString &dest_file = destDir+file;
+      if(getPluginVersion(shipped_file) > getPluginVersion(dest_file) ) {
         qDebug("shippped %s is more recent then local plugin, updating", qPrintable(file));
-        if(QFile::exists(destDir+file)) {
-          qDebug("Removing old %s", qPrintable(destDir+file));
-          QFile::remove(destDir+file);
+        if(QFile::exists(dest_file)) {
+          qDebug("Removing old %s", qPrintable(dest_file));
+          QFile::remove(dest_file);
         }
-        qDebug("%s copied to %s", qPrintable(shipped_file), qPrintable(destDir+file));
-        QFile::copy(shipped_file, destDir+file);
+        qDebug("%s copied to %s", qPrintable(shipped_file), qPrintable(dest_file));
+        QFile::copy(shipped_file, dest_file);
       }
     } else {
       // Copy icons
diff --git a/src/src.pro b/src/src.pro
index 8acf6a8bd..b4c28a140 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -108,6 +108,9 @@ QT += network
 
 DEFINES += QT_NO_CAST_TO_ASCII
 
+# Fast concatenation (Qt >= 4.6)
+DEFINES += QT_USE_FAST_CONCATENATION QT_USE_FAST_OPERATOR_PLUS
+
 # Windows
 # usually built as static
 # win32:LIBS += -ltorrent -lboost_system
diff --git a/src/transferlistfilterswidget.h b/src/transferlistfilterswidget.h
index 978230513..a0f42ee4f 100644
--- a/src/transferlistfilterswidget.h
+++ b/src/transferlistfilterswidget.h
@@ -172,19 +172,19 @@ public:
     vLayout->setSpacing(2);
     // Add status filters
     QListWidgetItem *all = new QListWidgetItem(statusFilters);
-    all->setData(Qt::DisplayRole, tr("All") + " (0)");
+    all->setData(Qt::DisplayRole, QVariant(tr("All") + " (0)"));
     all->setData(Qt::DecorationRole, QIcon(":/Icons/skin/filterall.png"));
     QListWidgetItem *downloading = new QListWidgetItem(statusFilters);
-    downloading->setData(Qt::DisplayRole, tr("Downloading") + " (0)");
+    downloading->setData(Qt::DisplayRole, QVariant(tr("Downloading") + " (0)"));
     downloading->setData(Qt::DecorationRole, QIcon(":/Icons/skin/downloading.png"));
     QListWidgetItem *completed = new QListWidgetItem(statusFilters);
-    completed->setData(Qt::DisplayRole, tr("Completed") + " (0)");
+    completed->setData(Qt::DisplayRole, QVariant(tr("Completed") + " (0)"));
     completed->setData(Qt::DecorationRole, QIcon(":/Icons/skin/uploading.png"));
     QListWidgetItem *active = new QListWidgetItem(statusFilters);
-    active->setData(Qt::DisplayRole, tr("Active") + " (0)");
+    active->setData(Qt::DisplayRole, QVariant(tr("Active") + " (0)"));
     active->setData(Qt::DecorationRole, QIcon(":/Icons/skin/filteractive.png"));
     QListWidgetItem *inactive = new QListWidgetItem(statusFilters);
-    inactive->setData(Qt::DisplayRole, tr("Inactive") + " (0)");
+    inactive->setData(Qt::DisplayRole, QVariant(tr("Inactive") + " (0)"));
     inactive->setData(Qt::DecorationRole, QIcon(":/Icons/skin/filterinactive.png"));
 
     // SIGNAL/SLOT
@@ -198,10 +198,10 @@ public:
 
     // Add Label filters
     QListWidgetItem *allLabels = new QListWidgetItem(labelFilters);
-    allLabels->setData(Qt::DisplayRole, tr("All labels") + " (0)");
+    allLabels->setData(Qt::DisplayRole, QVariant(tr("All labels") + " (0)"));
     allLabels->setData(Qt::DecorationRole, QIcon(":/Icons/oxygen/folder.png"));
     QListWidgetItem *noLabel = new QListWidgetItem(labelFilters);
-    noLabel->setData(Qt::DisplayRole, tr("Unlabeled") + " (0)");
+    noLabel->setData(Qt::DisplayRole, QVariant(tr("Unlabeled") + " (0)"));
     noLabel->setData(Qt::DecorationRole, QIcon(":/Icons/oxygen/folder.png"));
 
     // Load settings
@@ -257,11 +257,11 @@ public:
 
 protected slots:
   void updateTorrentNumbers(uint nb_downloading, uint nb_seeding, uint nb_active, uint nb_inactive) {
-    statusFilters->item(FILTER_ALL)->setData(Qt::DisplayRole, tr("All")+" ("+QString::number(nb_active+nb_inactive)+")");
-    statusFilters->item(FILTER_DOWNLOADING)->setData(Qt::DisplayRole, tr("Downloading")+" ("+QString::number(nb_downloading)+")");
-    statusFilters->item(FILTER_COMPLETED)->setData(Qt::DisplayRole, tr("Completed")+" ("+QString::number(nb_seeding)+")");
-    statusFilters->item(FILTER_ACTIVE)->setData(Qt::DisplayRole, tr("Active")+" ("+QString::number(nb_active)+")");
-    statusFilters->item(FILTER_INACTIVE)->setData(Qt::DisplayRole, tr("Inactive")+" ("+QString::number(nb_inactive)+")");
+    statusFilters->item(FILTER_ALL)->setData(Qt::DisplayRole, QVariant(tr("All")+" ("+QString::number(nb_active+nb_inactive)+")"));
+    statusFilters->item(FILTER_DOWNLOADING)->setData(Qt::DisplayRole, QVariant(tr("Downloading")+" ("+QString::number(nb_downloading)+")"));
+    statusFilters->item(FILTER_COMPLETED)->setData(Qt::DisplayRole, QVariant(tr("Completed")+" ("+QString::number(nb_seeding)+")"));
+    statusFilters->item(FILTER_ACTIVE)->setData(Qt::DisplayRole, QVariant(tr("Active")+" ("+QString::number(nb_active)+")"));
+    statusFilters->item(FILTER_INACTIVE)->setData(Qt::DisplayRole, QVariant(tr("Inactive")+" ("+QString::number(nb_inactive)+")"));
   }
 
   void torrentDropped(int row) {
diff --git a/src/transferlistwidget.cpp b/src/transferlistwidget.cpp
index bb1fcff31..c3d51a47e 100644
--- a/src/transferlistwidget.cpp
+++ b/src/transferlistwidget.cpp
@@ -295,7 +295,7 @@ void TransferListWidget::updateMetadata(QTorrentHandle &h) {
 }
 
 void TransferListWidget::previewFile(QString filePath) {
-  QDesktopServices::openUrl(QString("file://")+filePath);
+  QDesktopServices::openUrl(QUrl(QString("file://")+filePath));
 }
 
 int TransferListWidget::updateTorrent(int row) {
@@ -584,9 +584,9 @@ void TransferListWidget::torrentDoubleClicked(const QModelIndex& index) {
     break;
   case OPEN_DEST:
     if(h.has_metadata())
-      QDesktopServices::openUrl("file://" + h.root_path());
+      QDesktopServices::openUrl(QUrl("file://" + h.root_path()));
     else
-      QDesktopServices::openUrl("file://" + h.save_path());
+      QDesktopServices::openUrl(QUrl("file://" + h.save_path()));
     break;
   }
 }
@@ -693,7 +693,7 @@ void TransferListWidget::buySelectedTorrents() const {
   foreach(const QString &hash, hashes) {
     const QTorrentHandle &h = BTSession->getTorrentHandle(hash);
     if(h.is_valid())
-      QDesktopServices::openUrl("http://match.sharemonkey.com/?info_hash="+h.hash()+"&n="+h.name()+"&cid=33");
+      QDesktopServices::openUrl(QUrl("http://match.sharemonkey.com/?info_hash="+h.hash()+"&n="+h.name()+"&cid=33"));
   }
 }
 
@@ -1257,7 +1257,7 @@ void TransferListWidget::saveLastSortedColumn() {
   else
     sortOrderLetter = QString::fromUtf8("d");
   const int index = header()->sortIndicatorSection();
-  settings.setValue(QString::fromUtf8("TransferListSortedCol"), QString::number(index)+sortOrderLetter);
+  settings.setValue(QString::fromUtf8("TransferListSortedCol"), QVariant(QString::number(index)+sortOrderLetter));
 }
 
 void TransferListWidget::loadLastSortedColumn() {