I'm writing a little app that takes aerial photos and constructs something like a google map out of them. I'm adding QPixmapItems to my graphics scene, and the scene is connected to a qgraphicsview. Everything works great until I scale or rotate the qgraphicsview, the performance just goes to absolute crap. The qtdemo "ported canvas" seems to be able to zoom and rotate pixmaps without any loss of performance at all. Of course, I'm using 6megapixel pictures, not little tiny pixmaps, but I wouldn't expect it to get so slow. Anyone have any ideas what I'm doing wrong?

With rotating, if I rotate back to the initial orientation, the performance goes back up, with zooming (calling qgraphicsview->scale and using scaling factors 0.5 and 1.5) as soon as I scale it the first time, it gets realy slow, and scaling back to the original scale still results in slow performance.

Any help with this would be greatly appreciated - this is a bit of a rush job - has to be working by next week

Thanks
Andrew