The LineSeries uses a Path to draw its line. The slow performance is due to this Path, which is a framework element and there is nothing you can do to increase its productivity.
Basically when you have big amount of points that you want to visualize in the chart component we recommend using the built-in data sampling functionality provided as part of the external ChartDataSource
control. Here is an example how to use ChartDataSource with series provider:
SamplingThreshold set to 30 means that all data items of single series will be combined into 30 data points.
You can also try to set the RenderMode property of the series to Light.
I hope this helps.
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