In newer versions of the control you have the option to enable line sampling:
line.SamplingMode = SeriesSamplingMode.Enabled;
and / or to enable hardware accelerated rendering:
nChartControl1.Settings.RenderSurface = RenderSurface.Window;
So you may consider to upgrade. We would recommend you to test whether newer versions of control can meet your performance requirements (the control works with 1M+ data points without a problem). If it covers your requirements please contact firstname.lastname@example.org
for pricing / special promotions / discounts etc.
Hope this helps - let us know if you have any questions or meet any problems.
Nevron Support Team