The Curve Collector is more efficient at handling scenes with many curves.
Override sets are ideal for complex scenes containing many curves. This scene represents a cornfield that contains many Paint Effects strokes that have been converted to curves. It is possible to render this many curves easily with MtoA using override sets.
Note:
More tutorials on rendering curves can be found here.
Select the curves and create a Maya Set for them.
In the Arnold attributes for the Set, select Add. The 'Add Override Attribute' window will open (it may take a moment to open depending on how many curves are in the scene). Once it has opened, click on AiRenderCurve and then click on Add at the bottom of the window.
Open up Extra Attributes underneath the Arnold attributes, and you should see the newly created Ai Render Curve attribute. Enable it. To assign a shader to the curves repeat the above process but add AiCurveShader.
Finally, you may want to add an Ai Curve Width attribute to increase the width of the curves. In this case, an Ai Mode has also been added to give the curves some rounded thickness.