Hi,

another way how to solve this is the following "dirty" trick.
You can modify the QT source code for QLineSeries.
Search for "linechartitem.cpp", function "LineChartItem:aint".
Comment the line:

painter->drawLine(m_linePoints.at(i - 1), m_linePoints.at(i));

and add the following line instead:

painter->drawPoint( m_linePoints.at(i));

Then recompile the QT.
As the result you should get a scatter plot for QLineSeries which works fast ;-)

--
Cheers,
Garfungiloops