There are a couple options that a lot of Dynas had when they left the factory for surfacing.
The first is G61.1 which is High Precision mode. Gets called on a line by itself before the actual feed cuts begin. It will do a better job of slowing the feed rate near corners. There are a couple parameters that adjust how much the machine will slow down for a corner which I'll have to go look up.
The other option is G5 for High Speed mode. Again, gets called on a line by itself just before the feed cuts begin. G5 P1 turns it on, G5 P0 turns it off. It is supposed to make smoother motion for surfacing applications like you're doing.
I'm guessing you're DNCing that file? On my machines, the highest baud rate that would DNC is 9600. I tried at 19200 baud but the M3 control isn't sophisticated enough to handle that much data and move the machine at the same time. In other words, it can walk and chew gum at the same time, but it can't walk very fast.