Check perfomance of QwtPlotCurve with setPaintAttribute for displaying large data

[Uwe]

Antialisasing is a substantial performance killer and does not make much sense in your case - so the first thing you should do is to turn it of. Using a pen width > 1 is another well known problem - one that is not used in your code.

A general way to improve rendering is to use a hardware accelerated paint engine. On Unix systems this is pretty easy by using the X11 paint engine, that is available in Qt4 or Qt >= 5.10. Unfortunately Qt development decided to make the slow software renderer being the default even on X11 systems, where you have a much better option. On Windows you have to use an OpenGL canvas - or at least have to use the QwtPlotCanvas::OpenGLBuffer option you can find in SVN trunk.

The FilterPointsAgressive/FilterPoints flags make use of the fact, that when rendering a curve with many points many of them will end up at the same position as others. But for a plot with many curves of a limited number of points these flags won't help much.

Enabling the MinimizeMemory flag is counterproductive in terms of performance and is of no value when having curves with only 1000 points.

Uwe