Is the air cutting being generated by the rounding toolpath? If so, then one easy fix is to set the zero point for the long axis in the machine controller to where the rounding should actually start, and reduce the length of your part by that amount. So, for example, if your square area should be 4 inches long, and the long axis on your machine is Y, then go to Y0, move the axis 4 inches, and reset Y0 to the new point. Reduce the length of your leg by 4 inches.
For the air cutting on the part past the square area, the "Optimized Raster" option in the rounding toolpath is supposed to address this problem. It does require that you set up your part on the rotary in the right orientation so it cuts off the corners.
Other thoughts to reduce machining time are to use the largest bits possible for all operations. For example, for rounding I use a 1.25" surface cutting bit. For long curves and any coves where they will fit I use core box cutting bits from 1" to 1.5" in diameter. Only use your small bits to clean up corners and to carve areas where the big bits won't fit.
I can't tell from your picture how you're cutting the spirals, but if you're carving them with 3d toolpaths, and they're regular spirals, then that's kind of a waste of time. The can be cut much faster, and with a better finish, using cutters specific to cutting spirals...they're called barley twist and rope twist cutters, and you can buy them from Magnate. Then you can use the Spiral Layout and 2d toolpaths to cut the spirals. The main limitation is that the spirals will have to start no less than 1/2 the cutter diameter from the square ends. Most people hide this transition with a cove.
D&S Artistic Woodworking http://www.dsartisticwood.com