Replot large wav file data

[Uwe]

I am trying to move a marker around 100 ms (replot every 100 ms) to synchronize with the audio. Somehow the marker is moving very slowly.

When the marker is the only thing, that is moving you should cache the scene below the marker in a pixmap. If you implement the marker with a QwtPlotPicker, you don't have to implement the cache yourself, otherwise overload QwtPlot::drawItems().

Uwe