I recently had to do a very deep (98mm) 3D contouring job, and the tool did a full retract and plunge after each raster pass. It did this in both the roughing and finishing toolpaths. It was a huge time sink, with eighty percent of the machining time being the retracts & plunges, even with a very fast plunge rate. All the limits were set correctly with 2mm clearance all around for rapids and safe Z.
In the future I could manually remove the Z moves in a text editor, but is there a way to keep the tool down close to the workpiece? Am I missing something? It's a pain to edit.