Post processing of G - code

Is there software in the low cost form that I as a hobbist can use to
process the G-code prior to machining/engraving?

I have figured out how to create a dxf file and then use the MaxNc
mill program to create the G-code. The problem I see now is the
milling machine is doing the cuts in the order they were initially
drawn, ie. jumping around. For a small file, selecting the
lines/curves in the order I want them machined is fine. I have have
large graphics that I would like to engrave and they would be very
time consuming to select every line individually.

Thanks,
Bob