Yep, I usually have it set to 12 but I just tried 4 and it’s the same deal.
This particular gcode file (Inkscape generated) just sends the tool around in a big circle (almost the full size of the machine 70cmx70cm) as fast as it can go. I’ve tried it successfully on both the old Marlin and GRBL. It’s pretty smooth.
It looks like (on the lower Jerk setting anyway) it’s stalling at the end of each arc. segment.
It’s entirely possible I’ve screwed up a setting for my machine, since it’s a little bit custom, but straight moves seem OK.