As per title, what are your suggestions for speeding up the aux nozzle print time? Is there any other settings besides Max Volumetric Speed and inner/outer wall print speed? What are some of the other best practices?
The aux nozzle is mainly limited by the slow accelerations, which affects especially smaller or intricate parts. And you can’t go much faster without sacrificing quality. On big straight lines you could try increasing wall and infill speed. But the bowden extruder is naturally limited in performance compared to direct drive.
BambuLab have clearly advertised it with that implication, so I think it is most reasonable to accept the lower performance.
You can try the usual tricks such as modifying infill for non structural stuff etc for faster prints but getting the actual extruder to print faster is really set by design and akin to trying to make a sloth sprint the 100 meters
Usual I am getting around 2x time difference, but also depend from the model.
In the summary for the slice you can see statistic for what is taking the most time, and see if you can improve it or no.
And Alex_vG is right most of the time you can not improve because of the slow acceleration.
The acceleration profile is correct to be limited IMO. Higher accel during printing demands higher precision in PA, you just cannot and will not get it out of that stupid little tube that changes frictional area as the toolhead moves around in XY and that noodle slaps around the inner diameter.