What's the exact purpose of the analog signal? Do you want to use it as a gear master in electronic gearing mode? In fact this might be an option to speed up your sine generation. You should give it a try.
In contrast reading the analog input in software won't improve the performance (it probably will become even worse).
Contouring always runs onboard. I can't think of a method that would improve the performance of the sine generation by combining onboard programming with contouring, so I don't know exactly what you are referring to. Could you please tell me, where you have found the hint that you are referring to?
Thanks,
Jochen
