I have run jobs using the Fusion 360 Smoothing option that, in some cases, cuts the Gcode down dramatically. I've seen no obvious difference in results between smoothing on and smoothing off with the same job while code size sometimes dropped like a rock if the work involved a lot of arcs. Does this not make use of curves? If so, suggests GRBL handled them pretty well.
I should add, too, that the particular job where I had code size drop from 2.6MB to a few hundred kilobytes not only ran fine, but it helped Chilipeppr a LOT. Despite a fast computer, I was finding the buffer being left empty repeatedly on those big jobs and had to strip Chilipeppr down extensively (turn off tool path rendering, pre-load the buffer with more lines, etc) prior to the Smoothing version of the g-code.