I'm not sure if this has been brought up before, but one feature I'd like to see is a speed setting specifically for the infill based on the extrusion amount/length. What I mean is based of the distance between a direction change during infill, the speed adjust based on a users min and max infill speed. So if a distance between two side parameter is say 4cm the speed for that would be 45 mm/s (your max set infill speed) and if the distance was 3mm, the speed would be 10 mm/s. And any distance in between would be set based on the relation to the distance and your set speed range.