Ok, I found the culprit and it has nothing to do with your code, you already knew that but I didn't haha
it appears that my post processor is adding an extra line after the M05 and it has another M05 and M30 and for whatever reason the time multiplies for each of those commands, it is easy enough to edit my post and delete the last line but not sure why sheetcam is adding that extra line, also don't understand why the M30 is effecting the time counter?
N0010 (Filename: circle.tap)
N0020 (Post processor: Mach3 plasma no Z.scpost)
N0030 (Date: 28/10/2019)
N0040 G20 (Units: Inches)
N0050 G53 G90 G91.1 G40
N0060 F1
N0070 S500
N0080 (Part: circle)
N0090 (Operation: Outside Offset, LAYER_1, T1: Plasma, 0.04 in kerf)
N0100 G00 X-0.0590 Y4.9645
N0110 M03
N0120 G04 P150
N0130 G01 X-0.0200 Y5.1607 F100.0
N0140 G02 X-0.0200 Y5.1607 I5.1807 J-0.0000
N0150 G03 X-0.1480 Y5.2887 I-0.1280 J0.0000
N0160 M05
N0170 M05 M30
Thanks again