Cut down number of signal emits

src/gui/transferlistmodel.cpp

@@ -325,6 +325,8 @@ void TransferListModel::handleTorrentStatusUpdated(BitTorrent::TorrentHandle *co
 void TransferListModel::handleTorrentsUpdated(const QVector<BitTorrent::TorrentHandle *> &torrents)
 {
     const int columns = (columnCount() - 1);
+
+    if (torrents.size() <= (m_torrentList.size() * 0.5)) {
         for (BitTorrent::TorrentHandle *const torrent : torrents) {
             const int row = m_torrentMap.value(torrent, -1);
 
@@ -333,6 +335,11 @@ void TransferListModel::handleTorrentsUpdated(const QVector<BitTorrent::TorrentH
 
             emit dataChanged(index(row, 0), index(row, columns));
         }
+    }
+    else {
+        // save the overhead when more than half of the torrent list needs update
+        emit dataChanged(index(0, 0), index((rowCount() - 1), columns));
+    }
 }
 
 // Static functions