When v-carving small serifs, the toolpath at the end of each of them is a short quick up/out and back down/in motion that can cause 'jiggle' in the machine. This is more evident on a larger tool, but can still be abrupt enough on a desktop to impart some vibration. Adjusting just the move ramp speed in VR will not alleviate this. When I do small to medium v-carving on my PRS4896, I load a completely different set of ramps that make those spots smoother and sort of mushy in motion.
Along with adjusting the move ramp speed a bit, try adjusting the move ramp rate, 3D ramp threshold, and slow corner speed. Attached is what I run, but it may not be optimal for a desktop, so use it as a template and find what works best for you.
Issue a 'US' to save your current/default settings before changing the ramp values and that way you'll have a set of 'Standard' ramps to revert to. I take that saved file and delete all but the VR line and save it as a custom cut file with the name of the intended ramp settings within. That way I can load it or any other ramping scheme (3D, V-Carving, or Standard) as needed.
Also, use the same feedrate for the Z as you do for XY. This keeps the XY from having to slow down for the Z axis and helps keep a more even flow throughout the cut.
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