GDI+ Curve Wrapping

Question

Hi, I'm creating a graphing application using ZedGraph, which uses GDI+. If a curve is overflowing past the chart, I wrap it around to the other side. I do this by clipping the chart and just redrawing the curve as many times as it needs to wrap.

for(int i=startShift; i<=endShift; i++);
{
   g.TranslateTransform(chartWidth,0);
   g.DrawCurve(...);
}

This works, but it's slow, and I think g.DrawCurve is the culprit because it's running a spline interpolation algorithm everytime. Can I force it to only calculate once? Or do I need to draw the curve once to an offscreen buffer and just have the loop draw the buffer?

Thanks.