"A toolpath would choke on a multi-million polygonal count, where it would be a breeze on the same NURBS surface, to acheive the same "curvature resolution", at say, .0001."

An older machine with a hardware controller would choke on that, but it also would not be using splines either. With a modern PC based CNC controller, the file size is irrelevant as long as the PC can send the data fast enough to the machine.

Of course using smaller linear moves increases the file size of the toolpath. However, just because the toolpath file size is large does not mean it cannot be machined sucessfully. Perhaps your system uses arcs and straight line segments? Using arcs would account for a smaller toolpath file size.

Can you post some of the G-code?