I have a set of 50,000 data points that I would like to plot and connect the points with a line. Once the number of points surpasses about 40,000, the performance of the UltraChart becomes very sluggish. It takes several seconds to redraw when moving or resizing the window.
Yes, unfortunately with so large data the chart becomes slower. The things you can do to optimize the performance is disabling the tooltips:
this.ultraChart1.Tooltips.Display = TooltipDisplay.Never;
http://help.infragistics.com/NetAdvantage/WinForms/2010.1/CLR2.0/?page=Chart_Optimize_the_Rendering_Speed.html
Also make sure you are not using Spline chart. If you are using Scatter chart set:
this.ultraChart1.ScatterChart.LineAppearance.Thickness = 0;