[PyQt] QGraphisView performance

[Nahuel Defossé]

Hi,
I'm trying to display a map on a QGraphicsView widget having some scrolling 
and zooming. I need very basic interaction, add points, remove points, maybe 
a contextual menu. The issue I'm experiencing is that zooming and scrolling 
when on high zoom values is SLOW. 
For zooming I use view.setMatrix(QtGui.QMatrix().scale(factor, factor)) where 
factor > 1)
At first I tried to show directly the map I converted from a DFX file, a big 
SVG, using QtSvg.QGraphicsSvgItem but it was big and I knew it was gonna take 
a lot of CPU, it did. Then I tried with a pixmap, PNG 150k, which works 
better when no zoom is applied but starts to sorely degrade as the zoom 
factor raises.
I don't understand which is the best approach to achieve acceptable 
performance when you have to show big areas on this kind of canvas.
I'd highly appreciate any hints
Thanks
Nahuel