Non solid lines are very slow in GDI+ (and also GDI) compared to solid lines.
Also they are very slow in FireMonkey (specially in Android and iOS).

TLineSeries is more best suited to display few points (ie: less than 100) with 3D or 3D orthogonal perspective.

The fastest way to display lots of points is to use a TFastLineSeries instead of a TLineSeries, in 2D and with the DrawStyle property set to flAll:

Series1 ( TFastLineSeries )

Series1.DrawStyle := flAll;
Series1.Pen.Style:=psSolid;

You might also try disabling antialias. This can be done in two ways:

1) At Chart level:

    (Chart1.Canvas as TGDIPlusCanvas).AntiAlias:=False;

2) At FastLine series level:

Series1.FastPen := True;


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Here is a link to a demo using FastLine and OpenGL to display one million points repainted 130 times per second:

https://plus.google.com/+Steema/posts/eLycfRSKQws

Hi David, Thanks for the reply. We've tried both the options [setting TDBChart's anti alias property to false & using TFastLineSeries] suggested by you. But it is not working & chart response is too slow. Kindly note that we are using C++ Builder XE5 update 2 & TDBChart version is v2014.10.140213.

Created attachment 788 [details]
this video shows problem of drawing dashed lines ,here it is through chart wizard,wheras actual issue happens through code also

We've revised #2006 improving the DrawAllPointsStyle daMinMax performance for the FastLine:
http://bugs.teechart.net/show_bug.cgi?id=2006

Ie:

  Series1.DrawAllPoints:=false;
  Series1.DrawAllPointsStyle:=daMinMax

With it, drawing 1 million points takes 0.08 sec with solid line and 0.26 sec with dashed pen style.