Speed of Qwt plotting slows with many points

[Uwe]

The easiest way is to use QwtWeedingCurveFitter. It has to be used according to scale changes ( don't use QwtPlotCurve::setCurveFitter ). Depending on the tolerance parameter you can control the algorithm.

Of course such an algorithm is for line plots and not very effective for scatter plots.

Uwe

PS: note that using Qwt from SVN trunk reintroduces several optimizations, that have been removed in Qwt 6.0. They should have a notable impact on the performance of a line plot with many, many points.