Once we have a VD it is almost trivial to calculate 2D offsets. While the VD for n line-segments takes O(n*log(n)) time to calculate, the offset-generation is a simple "march" that takes O(n) time. In this "A" example it takes 24 milliseconds to calculate the VD and less than 1 millisecond to produce all the shown offsets. Input geometry in yellow, VD in blue. Offset lines in light-green and offset arcs in slightly darker green.
Here is a larger example where VD takes 1.3 seconds, and all offsets shown take 99 milliseconds in total to produce. It would be interesting to benchmark this against libarea or other open-source 2D offset solutions. (here all line/arc offsets in one green color, for simplicity)
Here is a third picture with offsets for a single offset-distance:
