Thanks philbobb for running that.

I just swapped solidworks/hsmxpress over to imperial in the document settings, output the same code and ran it. I lost 0.016" in Z.

If i run that code at 100% feedrate ((450mm/min zig-zag, 1000mm/min interpolate the circle) Z wanders up 0.060", run the code at 10% feedrate, Z wanders down 0.012". I think the pattern is Z not repeatable after this code.