Qwt: Is it possible to perform GUI operations from a separate QProcess?

[Uwe]

How does this compare with QwtPlotCurve::FilterPoints?

FilterPointsAggressive limits the maximum number of lines to be painted to: 4 * canvas.width() ( or height - depending on the orientation ).

So if you have a line plot where the samples are ordered in x or y direction the effect will be very significant for 1e6 samples.
If you have a scatter plot you could try what is done in the scatterplot example.

HTH,
Uwe