Hi Janosch,
Thanks for contacting Syncfusion Support.
While dynamically update the data points, the rendered series UIElement’s points are re generated for every updates (31 milliseconds). Since we have drawn single “Path” element for AreaSeries. So the CPU usage is increased while rendering the AreaSeries in UI.
When you update(insert) the same data point to the items source, Area Series(Path) will not be updated in UI (second round of update in your sample). But in this case, CPU usage increased in SfChart. We have considered this as defect and logged defect report for this. The fix for the issue will be included in our Volume 4,2016 main release which is estimated to be available on end of November 2016.
Regards,
Devi