I'm currently struggling with populating a qgraphicsscene with many (> 1Million) objects (Polygons, Lines, Points). What I've observed is, that when creating randomly 100000 Polygons, I'm already ending up withe 130MB memory consumption. (The simple example below is based on a default Qt-Project using the View.cpp of the chip-demo example)
Qt Code: 
  1. QtGrafikTestBasic::QtGrafikTestBasic(QWidget *parent): QMainWindow(parent)
  2.     {
  3.         ui.setupUi(this);
  4.         QSplitter *h1Splitter = new QSplitter;
  5.         QSplitter *vSplitter = new QSplitter;
  6.         vSplitter->addWidget(h1Splitter);
  7.  
  8.         View* view = new View("asdf");
  9.         h1Splitter->addWidget(view);
  10.  
  11.         QHBoxLayout *layout = new QHBoxLayout;
  12.         layout->addWidget(vSplitter);
  13.         setLayout(layout);
  14.         setCentralWidget(view);
  15.  
  16.         QBrush *brush = new QBrush();
  17.         brush->setColor(Qt::blue);
  18.         brush->setStyle(Qt::SolidPattern);
  19.         QPen *pen = new QPen();
  20.         pen->setWidth(0);
  21.  
  23.         srand ( time(NULL) );
  24.         int m_PolyWidth = 10;
  25.  
  26.         for (int i = 0 ; i < 100000; i++)
  27.         {
  28.             double lBaseX = rand() % ((int)floor(width())  - m_PolyWidth);
  29.             double lBaseY = rand() % ((int)floor(height()) - m_PolyWidth);
  30.  
  31.             QPolygonF polygon;
  32.             polygon << QPointF(lBaseX, lBaseY);
  33.             polygon << QPointF(lBaseX + m_PolyWidth, lBaseY);
  34.             polygon << QPointF(lBaseX + m_PolyWidth, lBaseY + m_PolyWidth);
  35.             polygon << QPointF(lBaseX, lBaseY + m_PolyWidth);
  36.  
  37.             scene->addPolygon(polygon, *pen, *brush);
  38.         }
  39.         view->view()->setScene(scene);
  40.      }
To copy to clipboard, switch view to plain text mode 

So what am I doint wrong here / where can I improve? I've read some posts of creating an own class like the chip-example, so I simply used the chip example but also there I've encountered the problem that as soon as I change the part which uniformly distributes the chips from
Qt Code: 
  1. item->setPos(QPointF(i, j));
To copy to clipboard, switch view to plain text mode 
to a random distribution
Qt Code: 
  1. item->setPos(QPointF(lBaseX, lBaseY));
To copy to clipboard, switch view to plain text mode 
, the memory consumption explodes also here...

So, what is the most performant and least memory-consuming way of drawing polygons, (poly-)lines and points in Qt?