Hi,
One note about NURBS curve rendering: actually a low point density can make rendering slower! A curve is split into segments before rendering. In the usual cubic case, each segment includes 4 points, from which the actual smooth shape is interpolated.
If the control polygon is very heavily bent to all directions, those 4 point base segments can become quite large in all dimensions. That makes raytrace optimizations harder (more curve pieces potentially travel across an examined volume of space). If the point density is sufficient, the 4 point NURBS segments become quite straight and 'thin' in some dimension(s).
This trick of increasing the point density works only when the original curve has very low point density. For example, cubic NURBS circles (or revolutions of a helix curve), which have only the minimal 4 points per 360 degrees are potentially slower than, say, 8 point circles. I would estimate that even higher point counts ( over 10 points/revolution) no longer help but start slowing down the rendering.
In the linear case, the lowest point count is naturally the fastest. Best regards, Vesa
