According to this the default max Z speed is around 19 in/min. What is maximum feed? - #2 by BartDring
So if I’m using 12 in/min plunge and increase that to 18 then theoretically I should see about a 33% improvement - any time associated with non-cutting travel.
Latest 3d carve said about 5 hours in Fusion then 6.5 hours in Easel 
I’m also finding that the linking operations (yellow lines in Fusion?) travel VERY slowly is Easel/X-Carve. Thoughts on which setting I might be missing? My roughing 3D adaptive clear suffers from this issue more than the detail pass.