This could be a question for the smoothie group as well but when engraving

This could be a question for the smoothie group as well but when engraving rasters I get a stutter in the speed. Any ideas? The link show a short video of what I mean. Thanks
https://www.dropbox.com/s/cg5k30qbw5v7sun/20170403_164657.mp4?dl=0

updated to the latest LW4 solved the problem. All going well.

The problem was under an older copy of LW4 then?

Seemed to be. I did notice later that I had the same issue but it wasn’t as bad.